Learn Spanish (Latin America): No hay nadie en la oficina.

In English, a double negative is usually incorrect, but in Spanish, it is actually required! When a negative word like nadie (nobody or no one) comes after the verb, you must put no before the verb. So, no hay nadie literally translates to "there isn't nobody," but it is the perfectly correct way to say "there is no one."

Can I just say "Hay nadie en la oficina" without the "no"?

No, you cannot. If nadie is after the verb, the no before the verb is mandatory. However, you can drop the no if you put the negative word before the verb. For example, if you changed the sentence to Nadie está en la oficina (Nobody is in the office), that would be perfectly correct without an extra no.

How do I know whether to use "nada" or "nadie"?

It depends on whether you are talking about things or people. Nada means "nothing" or "not anything," while nadie means "nobody" or "no one." Since we are talking about people being in an office, we use nadie here.

Why do we use "hay" here instead of "está"?