Life means some years given us by God to realise what really it is. It is like a journey, everyone has to reach destination. When their station comes they alight or they leave the world.
Shakespeare says "Life is like a stage, where all men and women are actor and actress. We come in world to perform our role, and after performing, we leave."
So life is a stage, a journey or we can say something that can not be defined in words. It can only be felt. Its meanings are different different for people.
We are here to perform our duty, to see and realise the beautiful word, to see twits, to see happiness and sorrow as well, to see the changing faces, to realise how people and situation changes with the passage of time.
If anyone realises the main purpose of life, he gets rid free from this physical world and become a part of universe.