What is a "Follower"?

Following means you're following another person's posts, kind of like being a fan. As Maggie pointed out when two people are following each other they become 'friends'.

Stalking is another matter entirely. It generally involves someone with ill intent who will eventually cause harm to the person of their focus. often it's a person with sociopathic or psychopathic tendencies who stalks another person, though sometimes it's just someone who is at heart a monumental a**hole.

I tend to avoid most social media, as it often spreads disinformation while polarizing people against each other and shared common needs, like having a functional government that works for the common good of all rather than a select few.

When you edit profile and check notifications, I didn't see anything indicating you can get notifications when following someone would alert you to when that person posts.

You can get email alerts for new threads and new posts, but I didn't see where it got any more granular.

I did some tests. It looks that this function is helpfull, if you are only interested in the posts/activity of one or two members. If you follow this path: Profile > Following you can see everything the people you follow do: posting, linking, following, becoming friend, etc. If the forum become very hudge, this will probabely be helpfull.