Cardano is a smart contract platform that runs the Ada cryptocurrency (ADA), which can be used to send and receive digital funds. Launched in 2015, Cardano is one of the 10 largest cryptocurrencies in the world in terms of market capitalization at the time of writing.
If you’re looking for somewhere to store ADA, there’s only one compatible wallet available for now. Known as Daedalus, it’s the official Cardano wallet. I don't know of any other wallet for now.