If you had perfect pitch, I would be able to play notes on a piano and you would be able to distinguish each. There is a continuum of perfect pitch - some may have perfect pitch after they have warmed up, others may retain their perfect pitch for a short time after they stop playing and others (apparently) always have it. In that aspect, it’s a little like memory.
Mozart and Ella Fitzgerald are two famous people you’ve likely heard who had absolute pitch though I have never read or heard anything that suggests either found it terribly useful. Of the musicians I know who have worked to develop it, it’s mostly kind of a party trick.
If you’re interested in perfect pitch, you should likely learn about relative pitch as well. Whereas perfect pitch refers to the ability to correctly distinguish a note cold, relative pitch refers to the ability to distinguish notes in relation to each other.