Let me dumb this down for you:
People in a state like California, which has a very large population, will be able to pass laws protecting abortion in their state legislators, which they elect and makes up a majority in their house and senate.
People in a state like Utah, which will elect conservative state legislators and will make up a majority of their house and senate, will be able to make their own laws on the subject and pass laws that the majority of people in their state support.
If a state does or doesn't want to see a law pass, they'll elect different state legislators.
People in California shouldn't be able to tell people in a completely different state what they can or cannot make laws about.
It's called federalism