Sometimes, the letter y is a CONSONANT, and other times it is a vowel. The rule for telling the two apart is simple: The letter y is a consonant when it is the first letter of a syllable that has more than one letter. If y is anywhere else in the syllable, it is a vowel.
Examples of Y as a Consonant
* yes
* yam
* yell
* yellow
* yogurt
Examples of Y as a Vowel
* gym
* my
* cycle
* baby
* hairy
* sky