As of now, there is no staking on Coinbase. Staking is the process of holding funds in a cryptocurrency wallet to support the operations of a blockchain network. When staking, one earns interest on their holdings.
The interest earned depends on the size of the holding, the length of time staked, and the overall health of the network. Staking can be done with any size holding, but generally, the larger the stake, the greater the reward.
Coinbase has not yet announced if or when they will offer staking to their customers. However, given that Coinbase is one of the most popular exchanges and wallets in operation today, it is likely that they will eventually offer staking services.
If Coinbase does offer staking, it would likely be a major boost to cryptocurrency adoption as more people would be exposed to the concept and could earn rewards for simply holding their coins in a wallet.
Whether or not Coinbase offers staking in the future, there are many other exchanges and wallets that currently offer this service. So if you are interested in earning rewards for supporting a blockchain network, you can still do so even if Coinbase does not offer staking.