Celo will have two native crypto-assets at launch:
1/ Celo Dollar, an ERC-20 like asset pegged to the US Dollar
2/ Celo Gold, an ERC-20 like asset similar to ETH in Ethereum
Celo has its own blockchain, which means the assets above live within the Celo ecosystem and bridges will need to be built to interact with other blockchains.
Transaction fees are can be paid in Celo Dollar or in Celo Gold. Celo Gold gets minted by the network at each block like other protocols. Celo Dollar supply is managed by the protocol based on demand for it.
Since the network hasn’t yet launched these assets are not yet listed on exchanges.
If you’d like to get Celo testnet Dollars and Gold you can faucet yourself here: https://celo.org/build/faucet. Note: these are testnet assets and have no economic value.