"Someone" is, in this case, a girl looking extremely confused.

Extremely confused girl says something in a language that, to an untrained ear, might sound some kind of Slavic, except it's not any of the existing earthly Slavic languages.

“Um,” Morty says astutely. “You don’t speak English, do you? ...parlez-vous Francais?”

...different language, this one some strange mix of Asian—and Latin-sounding?

Morty shakes his head, then pauses. “Is that a universal sign, shaking your head?” He tries a Gallic shrug instead.

Well, she seems to at least understand it well enough to mimic it and smile at him.

Oh no a cute girl smiled at him what do. He attempts to smile back, and mostly manages it.

”I... guess I’d better call Administration so a psychic can get your language and somebody can put you back where you came from? I don’t know why I’m talking out loud about this, I guess it just seems friendlier that way. Just, uh, sit tight.”

She did not understand a word of that so she'll just assume that since that didn't sound like a question he tried to say something reassuring. She makes a gesture with her hands that looks a bit like a very slow punch against her palm except with the little finger and thumb extended out, pauses to consider this, then stops and decides to just keep the smile going.

He goes over to a device on the wall and removes part of it and holds it to his ear, then presses some buttons on the wall part.

"Hi, this is Morty Halliwell - well, um, something exploded, obviously, and now there's a girl in my room who doesn't speak English and I think she might be from another universe. Yep. You're telling me, ma'am. I don't think she's dangerous, you don't have to- okay. Bye."

He hangs up the device gingerly and lolls his head back. "Great. Well, at least it'll be over quickly."

...ooh. He spoke into a thing on the wall and was probably talking to someone? That's interesting, what kind of magic is it?

None at all, apparently!

If she's looking for magic, there's actually surprisingly few magic objects here. Not the device on the wall, not the scraps of charred cardboard around Kaede's feet, not the flawless plate glass of the window. The only magic in the room besides her and her personal effects is Morty himself, and a general sort of haze of the stuff woven through the air.

There's also someone flying through the air in a corona of blue light, rapidly approaching the window. She's magical.

...wait, if it's not magical... then how...?

This is all so mysterious. She'll wait here and prepare an escape spell if she needs to.

The flying woman comes to the window and, in a flash of blue light, teleports into the room. She's holding a platinum rod topped with a star sapphire (both of which are extremely magical), and she squints at Kaede suspiciously. "This is the girl you summoned?"

"Yeah," Morty says.

The scepter glows, and a tendril of magic extends towards Kaede's mind.

No the fuck it doesn't.

The woman blinks and looks at the scepter. She shakes it a couple of times.

"Something wrong?" Morty asks hesitantly.

"She appears to have... nullified my translation spell. This could present a problem."

"Whoa. I didn't know she was magic."

"I did. Now shush."

Morty shushes. The woman floats gently to the floor and points at herself. "Elizabeth Carson."

Point at self. "Kaede," she says, using a name that sure sounds very normal for a locally Korean girl even though this girl is quite obviously not Korean. Then she pauses, clearly thinking about how to communicate something, then she decides to point at the rod, then tap her temple twice, then make a quizzical sound accompanied by a tilt of her head.

Mrs. Carson nods, then turns to Morty. "Elizabeth talk Mortimer," she says seriously.

"...what?"

"Go with it, Halliwell," she says. She turns back to Kaede and raises her scepter, which glows. "Elizabeth talk Kaede?" she asks.

Oooooooh. Okay, she starts doing the palm punch gesture again and stops herself again and goes back to the smile. Hopefully clear enough?

The tendril reaches out again, pokes her brain, and departs.

"Testing: can you understand me?" Mrs. Carson asks.

"Oh, yes. Neat spell, that's really cool, how does it work?"

"It essentially takes a pre-programmed understanding of the English language and implants it into your brain temporarily. The spell normally lasts only a day or so, but I can have a psychic associate of mine make it permanent if that turns out to be necessary. Where were you before Mortimer summoned you? Is anyone going to be urgently missing you, such that we should prioritize trying to send you back immediately?"

"No one's going to be missing me anytime soon," she says. "I was travelling between towns, not doing anything important. Implanting knowledge in one's brain, though, that sounds both useful and kind of terrifying."

"Yes, it can be very dangerous if misused. That's part of why I only use it for the translation spell, and only temporarily."

"What about other people though?"

"There aren't very many other people running around who are good enough at magic to manage this kind of spell. Most of them are either very careful with their powers, as a powerful wizard should be, or they are supervillains, who tend to show a notable lack of respect for the public good."

"Psychics can do it too, but they're even more heavily regulated," Morty says.

"What rate of... uh, people with terrifying powers to people who can't resist them do you have?"