An email provider is the company that does the technical stuff behind the actual sending and receiving of emails.
Many companies will have their own name in their email address, however, if you use a free provider this will often be the word that comes after the @ symbol in the address. Examples of free providers are @gmail, @outlook or @hotmail.
If you receive an email claiming to be from your bank or a large organisation that uses a free email provider this is telltale sign that the email is a scam. You can find out more about email scams here.