What's the purpose of your life?
There are two questions here. First, what is the purpose of life itself. Many have tried to answer this and there are millions of words written on this.
The purpose of your life is perhaps easier to understand, for it is limited to an assumed identity, you. This assumed identity has been programmed by your parents, teachers and society as well as the biology itself to charge it with a purpose. The biological entity acts for survival and procreation. This purpose takes on the shape of the world you know, live in and love. This world of action seems to have no end but if you reduce all the grandiose acts from exotic dinners to space flights to discovering dark matter, it comes to common denominator of biological progress.
This natural path of securing survival comes to somewhat of an end for many when the body feels secure. Until then, the answer to the question is simply taking one step after another towards this mundane goal of survival. You share this purpose with all living beings.
But more importantly, ask why has this question surfaced in your mind or rings a bell as something significant? Is it a call in response to struggles and suffering in the way of taking that step one after another? Or is it a call from somewhere deep? How can you tell? Just take a look, an honest look.
In either case, meditation helps. If it is due to resistance to mundane living, a deep look into impermanence significantly reduces the tension. If it is somewhat of an spiritual call from within. Look at what the answers may be and how these answers may change your actions now and in the future. Are you, for instance trying to solve a problem that doesn't exist?