Hi there, my car is 2002 fiat punto. when i hit the brake, there is a light sign coming on the dash board, which is a shape of light ball with a exclamatory mark in the middle, just wonder what problem is that, thanks

As per the manual this problem of Red circle with exclamation mark on car dash board belongs to problem in brake system.this is the indication to check the brake system. In the Fiat punto cars service manual it says as follows:-- Malfunction of the brake system.
Check break fluid, if that's not the problem
visit the dealer.
When it come up together with ABS light the ABS system needs to be checked. --------------- Most probably this problem is due to low brake fluid.BUT if the problem is same after filling the brake fluid then the brake system wiring needs to be checked.its wiring's are getting short somewhere. Thanks. you can rate this solution and show your appreciation.

It's telling you that there's a fault with your brakes. You'll need to consult the owner's handbook for further details as to possible causes.

As a first step though, check the brake fluid level: if it's below the minimum then top it up, but also be aware that normally it only drops below the minimum if the brakes are severely worn or if there is a fluid leak, so get the brakes inspected urgently by a knowledgeable person.