The sound represented by the letter <a> in the word <can> has three pronunciations:
 [ae] as in cat
 [I] as in sit
 [E] as in pet
The sound represented by the letter <y> in the word <you> is pronounced [y], which is also symbolized as [j]. Both [y] and [j] represent the same sound: as in yelllow.
Can you? [kaenju:]
Note, <y> is not pronounced as jello or Jewish.