Learn Portuguese (Portugal): A escola é perto do parque.

While estar is used for temporary locations (like where a person is right now), Portuguese uses the verb ser (which becomes é here) for permanent locations. Since a school doesn't move around, we use é. You might also hear the verb ficar used instead for permanent locations.

Where does the word do come from in this sentence?

The word do is a combination of the preposition de (of) and the masculine word for 'the' (o). To say "near the park", Portuguese literally says "near of the park" (perto de + o parque).

Do I always need to use de (or do/da) after perto?

Yes, if you are naming the place it is near! Just like the other location phrases in this lesson (ao lado de, em frente de), perto needs de to connect to the next noun. If you just want to say "The school is near" without mentioning the park, you drop it and just say A escola é perto.

If the school was near a feminine place like a pharmacy (farmácia), how would the sentence change?