The pronoun "es" (it) is usually used for a neuter noun.

Example:
Ist das Bett zu hart? - Nein, es ist nicht zu hart. (es = das Bett)

But:
Es gibt Pinguine.

In this sentence, "es" has a different function. Here it doesn't stand for a particular noun. It functions as the subject, without having any actual meaning. This construction is used frequently for impersonal phrases which have no other subject.