To label your post means that you categorize your post content into an index of a more general subject. These labels help to guide the audience to draw a big picture of what certain information they can get from reading your post.
You can label your post while you're creating a blog post. If you're using Blogger then you can find it on the right hand side bar under Post settings. Click on Labels, fill in the box, and click Done.
However if you forgot to label your posts don't worry, you don't need to edit your blog post. All you do is to go to your Posts section. Tick on the box which post you want to label, and then click Label icon on the header, and choose which label you want to add to your post or you can even add new label.
I found out about it the hard way !lol
Find more Blogging Tips on Bonjep's Lookbook!