First of all, tell us which kind of organisation you represent?
If it is a factory kind of organisation, obviously, for the period of 11 months he has worked, he will earn leave at the rate of one day for every 20 days physically present in the preceding 11 months and the amount equal to that should be paid to him along with his F&F. One more thing to be noted is that he will become eligible to earned leave only if he has worked for at least 220 days in the 11 months. or deciding this eligibility take the holidays and weekly off days days for which he was paid salary. If he was given lay off during this period, that will also qualify for the eligible period. But the number of leave he earns is strictly based on the days he was physically present for work.
Similar provisions are available in Mines Act or Plantation Labour Act.
In case of commercial establishment like IT firm, media etc, you have to refer the state Act on Shops and Commercial Establishments. Mostly it will be like, earned leave is due after 12 months of service. Hence is he has worked only for 11 months, he will not get it.