What’s going to happen with ETH2?

This is probably a super noob question so apologies in advance.

But what will happen to any ETH that someone owns when eth2 comes out?

Will it change and be like Bitcoin cash or whatever or will my ETH automatically be updated to eth2?

I’m sure this post is making some people want to cry with my stupidity but i want to buy some more ETH but I’m unsure if this 2 version change will things?

Thanks