You can find your answer here - http://zerodha.com/varsity/chapter/financial-ratios-part-3/
The price to earnings ratio (PE Ratio) is the measure of the share price relative to the annual net income earned by the firm per share. PE ratioshows current investor demand for a company share. A high PE ratiogenerally indicates increased demand because investors anticipate earnings growth in the future.
PE of Nifty is 23.66