Gmail doesn't have the Priority Inbox feature turned on by default. This feature divides the contents of your regular inbox into sections on your screen: Important & Unread, Important, Unread, Starred, and Everything Else. You can choose which of these to use. Gmail determines what you're likely to classify as important and places those emails in the Important & Unread section based on criteria such as how you've treated similar messages in the past, how the message is addressed to you, and other factors.
How to: Mark an email as important in Gmail with Google Workspace for Business
Every email has an importance marker just to the left of the sender’s name in the Inbox list. It looks like a flag or arrow. When Gmail identifies a particular email as important based on its criteria, the importance marker is yellow. When it doesn’t recognize it as important, it’s just the empty outline of the shape.
You can click the importance flag at any time and manually change the status. To learn why Gmail decided a particular email was important, hover your cursor over the yellow flag and read the explanation. If you disagree, simply click the yellow flag to mark it as unimportant. This action teaches Gmail which emails you consider important.
To enable Priority Inbox through Gmail settings: