Yes, you can jump over your opponent. In the case of mandatory movement effects, you are required to. You don't count the space your opponent is on as a movement, so the first space you move to is the space behind your opponent. Characters do not block movement, but walls (edge of the board) do
In this specific case, you have the choice to advance "up to" 3 spaces, including 0 as an option, so the movement is actually not mandatory, but you can absolutely jump over your opponent (1 space) and then advance up to 2 more spaces after that, assuming a wall doesn't stop you first
P.S. Page 26 of the rulebook is the one you want for these rules
EDIT: Changed post to apply more to this specific example
Words like "Advance," "pull," or "retreat" in this game simply determine the initial direction of the movement--towards or away from an opponent. Once the direction has been determined, movement happens in that direction, even if it means you jump over your opponent and continue forward.