What does y mean in espanol?

It depends, if you mean "y" as in the Word "and", it is pronounced like a "long e" in English (like yippee, or she, or me). If you mean "y" as in how to say "the letter y", then it is pronounced "ee- (like she or me) gr-ee-egg-ah"

If it's part of a longer Word than 'y' ('and'), it's not dissimilar to English 'y' in 'you',

e.g. hay (as English 'I') = there is/are;

hoy (like Oy! in English) = today

ayer (ahYAIR) = yesterday