Hi Rishabh
Operation "HRS" processes the number of hours field. You can use it to enter a particular value in the number of hours field and provide values from tables, Infotypes & get results from tables SALDO, TES, and so on.You can use operation HRS as a decision operation or as an operation to perform calculations and form balances.
for more details regarding this operation goto PE04 & give operation as HRS
Hope this Info
will be useful
Cheers 
Pradyp