Polygon has its own cryptocurrency, called MATIC, which is used to pay fees on the Polygon network, for staking, and for governance (which means that MATIC holders get to vote on changes to Polygon). You can also buy and sell MATIC via Coinbase and other exchanges.
The name MATIC comes from an earlier stage in Polygon’s development. After launching as Matic Network in October 2017, developers rebranded as Polygon early in 2021.