Vesting is Luna that was airdropped to your wallet during genesis, but is not yet released and cannot to be traded freely. You can still delegate, redelegate, and undelegate vested Luna.
To view your vesting amounts and vesting schedule, open Terra Station and connect your wallet. Make sure you are using the Phoenix-1 mainnet network
On the home page of Terra station, you can see the Luna that is vesting, and the corresponding vesting schedule.
Example: The following image shows Luna that is still locked in vesting: