I've been thinking about this because I've been asked a few times and always found it difficult to explain but at last I think I have the answer.
Me: Well you know how Twitter is a network for talking and insta is a network for pictures, YouTube is a network for videos etc
Them: yeh
Me: well Bitcoin is a network for money, the only difference is that instead of a company running it getting steamrollered by Governments it's a network that anyone can run a server on and use for themselves. Takes banks and Government totally out of the equation.
Thats my best shot so far. Have yet to test it out.