Eth2 refers to a set of interconnected upgrades that will make Ethereum more scalable, more secure, and more sustainable. These upgrades are being built by multiple teams from across the Ethereum ecosystem.
If you're a dapp user or ETH holder, you don't need to do anything. If you're a developer or want to start staking, there are ways you can get involved today.
All while keeping Ethereum's core ethos of decentralization.
Although each is being worked on in parallel, they have certain dependencies that determine when they will be deployed. Eth2 is not a migration or a single thing. It describes a set of upgrades being worked on to unlock Ethereum's true potential.
Source: https://ethereum.org/en/eth2/