In Cryptocurrency there are different types of proofs, what I am guessing you are familiar with is proof of work, which uses electricity consumption to answer mathmatical equations in hope of having the right answer to get the block.

Proof of stake is much more eco friendly, as it does not require you to buy expensive mining gear. In proof of stake, you "lock" up your coins, and your coins will validate transactions based on how many coins you hold, and you will be rewarded. The more coins, the more reward.

The coin is in a way kind of like the mining power for mining proof of work coins, the more coins, the more mining power.

Hope this helped!