When a validator is done validating the Primary Network it receives back the AVAX tokens it staked. Additionally, it may receive a reward for helping to secure the network by validating. Currently, the staking APY is roughly 9%, and a minimum delegation fee of 2% from users who delegated AVAX to the validator.
A validator only receives a validation reward if it is sufficiently responsive and correct during the time it validates. A validator must maintain at least an 80% uptime to receive rewards.
To have a validating node, the node must have a minimum of 2000 AVAX staked.
To learn more about Validators on Avalanche, please read the following article.
See the Avalanche token paper to learn more about AVAX and the mechanics of staking.