brakes

i have a problem with brakes . it just started wife is driving car says brake light came on and started dinging. i checked brake fluid filled it up but brakes still go right to the floor.don't see anything leaking from underneath. any suggestion.. 97 lesabrealso have problem with wipers hadto dissconnect battery now wipers won't shut off until i turn car off then they stay off till i turn them on again. any suggestions

How much brake fluid did you add? Was the reservoir empty?

Could be air in the system.
Could be the master cylinder is bypassing internally.

Is the park brake pedal fully retracted? Does the switch for the park brake pedal think it is retracted?