beep sound comes from laptop

Dear sir,

My laptop is Dell Vostro 1540. When i turn the power on, a beep sound comes 5 times and stops and again it beeps 5 times and stops and it remains continuous. When i press a key, the speed of beep sound gets slower and when release the key it becomes faster again.  So could u please help me out to make my laptop work properly.

Thanks and regards

Meghansh Bajaj