Liability reduces profit?

May I request someone to explain how does the liability reduces our profit in our P&L? Kindly help me in getting this basic.

Provision vs liability:For example... Is it not better to show it as Liability itself instead of creating a provision because by creating a provision my Net profit is directly going for a hit. Liability I am going to show only in balance sheet. My p&l is not affected. Please enlighten me on this understanding.