Cardano is a 3rd generation Blockchain and the ADA is their native cryptocurrency that feeds Blockchain level transactions!
Just as Bitcoin is the cryptocurrency on the Blockchain of the same name, in the case of the Cardano Blockchain, the cryptocurrency is ADA!

Source: https://medium.com/cryptostars/all-about-cardano-ada-explained-for-beginners-2022-b147bc118f19?source=rss——cryptocurrency-5