"Mi lányok vagyunk, ti pedig fiúk."

Translation: We are girls, and you are boys.

[CynthiaKin6]

why is 'leanyok' not correct?

[RichieMB]

Report it, I think leányok is correct.

[MrtonPolgr]

It's correct, be aware it's oldish/can sound like some literary cliché.

[Renardo_11]

I first encountered this form visiting Leányvár, the girls' fortress of the roman castle Kelemantia east of Komárom / Révkomárom. It's on the Slovak side since 1919.

[gephardt]

How about "we are girls and you boys?"

[TamsMar]

I think English requires a second 'are'

[ataltane]

It doesn't require it, but the form without the second 'are' is rather literary in style.

[flyingfisch_]

When does mi mean what and when does it mean we? Is that something i just need to get a feel for?

[Judit294350]

When does blue mean a colour and when does it mean sad? When does bear mean an animal and when does it mean to carry? Hungarian is the same as English in that way - most words have more than one meaning - some have more than a dozen.

You work it out from context. In this case "what" is meaningless in this sentence. Further the verb is vagunk and you are contrasting with ti.