The general 'it' [duplicate]
Solution 1:
It's usually called dummy 'it' or empty 'it'. More accurately, it is a dummy subject. It has no meaning, but provides a subject for a clause that otherwise wouldn't have one.
Solution 2:
It is a third-person, neuter pronoun. I had always assumed it was a definite article, so this was kind of neat to learn as a bit of nerd-trivia.
As for the first example, 'it' is associated with 'is,' so it functions as part of a to-be verb.