Staking means that you ‘stake’ your coins on the blockchain as part of a Proof of Stake (PoS) activity to secure the network. Which is different to traditional Proof of Work (PoW), which is how the Bitcoin blockchain works. Staking is the model of Proof of Stake blockchain, known as PoS.
To stake your cryptocurrencies you often need to keep them in a dedicated blockchain wallet. Some blockchains need you to keep that wallet online 24/7. Others with ‘cold staking’ allows you to keep your wallet offline and it will stake your cryptocurrencies and you will earn your rewards.