Hi,

If you think you are good in French then go for it but if you think you are not then skip it. Generally, choosing a second language in 12th boards is not compulsory but different schools have different set of subjects that they offer to their students, & you need to choose an easier subjects so it does not hamper your total percentage. If you don't know any other language & you feel French can serve you well, then go for it.

Hope this helps.