Sometimes you want to notify someone (private profile, brand’s Page or a group) in one of your posts and comments. That’s why there’s a little thing called mentions.
To mention a person, Page, or group, you have to type an @ in front of who you want to mention. You can type the whole name out, or select from the drop down list that appears.
You can also completely type out the person’s name with a capitalized first letter. Then, when the list appears, pick the person you want to mention. The benefit here is the engagement it can generate for you whether it’s your personal profile or brand!
Keep in mind that depending on a Page’s settings, you may not be able to mention it. The person, Page, or group you mention will get a private notification, and the post or comment may appear on their Timeline.