Arroba hotmail outlook

You're referring to the @ symbol!

In the context of email addresses, the @ symbol is used to separate the local part (the part before the @ symbol) from the domain name (the part after the @ symbol).

Here are some examples:

In both cases, username is the local part, and hotmail.com or outlook.com is the domain name.

The @ symbol is often referred to as the "arroba" in some Spanish-speaking countries, which is why you might see it used in this context.