Unlike in pool, the cue ball may not jump over a ball in snooker. Jumping balls in snooker is illegal.
It may jump, however, before striking the object ball provided it does not land on the far side of the ball. Also, even if it strikes the top of the ball, if it lands on the other side, it would still be considered a foul - and the player would receive the penalty value of the "ball on" (which would be a minimum of four points), or the penalty value of the ball struck; whichever is greater.
To clarify further, supposing the yellow were snookered by the black. If the player jumped over the black without touching it, that would be four away. If however the black were struck as the white jumped over it, that would be seven away as in a normal foul. If the white strikes a ball "on" fairly, then jumps over another ball, this is not a foul.
It is also possible for the white to jump onto a cushion and drop back onto the table. This is not a foul, and, if the "ball on" jumps onto a cushion, runs along it and drops into a pocket, the "ball on" is scored as normal. If, of course, a ball had been jumped over before this, it would be a foul.
If the cue ball jumps onto a cushion and comes back on the table, this is not a foul, but if it stays on the cushion, a foul is called and the white is played from hand.