Trying to set up email account. It’s asking me to go to mail account settings and enter a password. I don’t understand.

I can get emails on my laptop but not on my iPhone. My phone is updated to 15.1. I can’t get email account (gmail.com) when I try to add. It’s telling me no password entered for Gmail. And to go to mail account settings and enter a password. I don’t understand what that means.