Whose (something) is it?

In English, we have a lot of sentences like these: 

It’s my birthday!

It’s really nice out today.

...where “it” doesn’t have any particular meaning, but we need to use it. Asking “___ ___ is it?” is the question form for one of these sentences:

Whose birthday is it?

How nice is it outside?

We still need “it” in these sentences because the sentence needs a subject.

This phrase appears in these lessons: