Learn Spanish (Latin America): Los perros están en el parque.

Both ser and estar mean "to be," but we use estar (and its forms like están) to talk about physical locations. Since the sentence tells us where the dogs are located, we must use están.

Why does están have an accent mark on the 'a'?

The accent mark tells you to stress the last syllable when speaking (es-TÁN). Without the written accent, the standard rules of Spanish pronunciation would make you naturally stress the first syllable (ES-tan).

Does the word en always translate exactly to "in"?

Not always! The Spanish word en is very flexible and can mean "in," "on," or "at." In this sentence, en el parque can mean either "in the park" or "at the park" depending on how you would naturally say it in English.

If the group has both male and female dogs, do we still use los perros?

Yes! In Spanish, the masculine plural form (los perros) is used for a group of all male dogs, or a mixed group of males and females. You only use the feminine las perras if every single dog in the group is female.