All fruit trees set more fruit than they can actually sustain. They then drop part of this to allow the balance of the crop to grow well.

Moon_grower is probably right, but you might also check the irrigation, to make sure it is sufficient. Figs are fairly drought tolerant, but they may need extra help when young, or in extreme weather. If this is the first year you are dealing with them, you may want to find out if they are a variety that needs pollination, too.