Why do you see ripples when you place vibrating tuning fork in water?

Because if the tuning fork is vibrating, it is moving back and forward. Putting it into contact with water will move that too and set up a wave (or ripple). It'd even work (to an extent) if you held the tuning fork above the water.

In the same way listening to very loud music with a lot of bass can make your curtains ripple.