There are a variety of emails that you get on Gmail. So, If you’re getting emails of various kinds or types then you’ll need to label them and if you’re not able to do so then you might want to contact Gmail support , however all you have to do is click on the email that you want to label and then click on the ‘lying pentagon’ icon which represents label. https://www.yahoohome-page.com/gmail-support-phone-number/