USDC.e on Avalanche is a token representing USDC on Avalanche that was bridged from the Ethereum blockchain via the Avalanche Bridge.
For example, when sending USDC over the bridge to the Avalanche Network, it will appear as USDC.e once the transaction is completed.
If you don't immediately see the USDC.e after a successful transaction, you may need to add the token to the wallet you are using so it shows your balance of USDC.e.
Note that to send USDC.e back, is the same process but in reverse, resulting in USDC.e turning into USDC.
You can swap USDC.e for Avalanche native USDC using DEXs on Avalanche.