What does coquí mean in Spanish?

"Coquí" doesn't really have a specific meaning in Spanish. It's the onomatopoeic name for a type of small tree frog found in Puerto Rico and other Caribbean islands.

The name comes from the characteristic sound the frog makes, which is a high-pitched "co-quí".

It's like saying "chirp" for a bird or "meow" for a cat - it's the sound the animal makes, not a direct translation.