He's not actually following you, it's a spam reply he put on a bunch of people's posts.
....However, to answer your question, just click on someone's name and that opens a small window where you can click on their image to see their profile, click on 'follow' to follow, or click on 'mute' so you don't see their posts.
no bro I have my channel also on YouTube,well I am new here so don't know much about this platform