Ethereum uses proof-of-stake, so holders can lock up ETH to help secure the network and earn rewards in return.
Running your own validator requires 32 ETH and technical setup. It offers the highest rewards but also the most responsibility.
Pools let you stake smaller amounts together with others, sharing the rewards proportionally. This is a good middle ground.
Liquid staking gives you a token representing your staked ETH, so your capital stays usable in DeFi while earning staking rewards.
For most people, a staking pool or liquid staking service through a reputable wallet is the easiest way to start with less than 32 ETH.
Staking is a way to earn yield on ETH you plan to hold, but it involves lockups and smart-contract risk, so research before committing.