is it as simple as, we can have different email addresses:
Yes and no. Mostly no.
You can, and normally should, create a new receiving address every time you receive money. You could, but normally shouldn't, create a new email address every time you want to receive an email message.
- A street address identifies a specific place.
- An email address identifies a specific person
- An IP address identifies a particular network port on a computer
- A bitcoin address doesn't identify anything.
The purpose of a Bitcoin address is unlike most other things for which we use the name "address". A Bitcoin address is really just like a random number in most regards. It's just a seemingly random number that in fact has a useful mathematical relationship to a really random number that is secret.
so you use them as accounts for yourself
You can use them that way. But that's something extra you do outside the Bitcoin network. There are also privacy issues if multiple people or businesses send money to the same one of your addresses. So you shouldn't use an address as a "sales" account for example.
nobody know who is who with these "addresses"?
Correct. But if you reuse addresses, information about you and your money leaks out.