It is easiest to think of Bitcoin as being digital cash. Like cash it is hard to track and hard to reverse without the consent of those involved in a transaction. Unlike cash it can be sent from person to person electronically over the internet. Critically, this is a direct person to person transfer and can happen without requiring any intermediary. There is no central control or organisation running Bitcoin. Further, you don’t need to be a person to open a Bitcoin account. Anything from cars to kettles could, and in fact will, use Bitcoin so long as they have an internet connection.
Bitcoin works by using a technology called a blockchain. A blockchain is nothing more than a distributed database with the special property that existing records in it are immutable. Anyone and everyone can have a copy of the Bitcoin blockchain and every transaction in it is public. There is pretty good anonimity because all a transaction shows are Bitcoin addresses and there is no direct link to individuals.