--description--

There are is used when talking about the existence of multiple things or places in a particular location. For example:

There are two emails in your inbox. - Two emails exist in your inbox.

--questions--

What phrase would Maria use to indicate the existence of multiple parks near the office?

There is a park.

There is is used for singular nouns, not plural.

They are parks.

While they are is correct, it's not the phrase used in this context.

There are a park.

There are is the correct phrase for indicating the existence of multiple parks near here.

There are parks.