Think of it as "He is going after me". You can't remove the 'after' there (won't make sense if you did), just like in this sentence.
Not the same meaning in all cases, but it helps to remember this.
You can say "Han följer mig på Facebook" for sure, but the meaning is a bit different, I guess.
What is the difference between "Han följer efter mig" and "Han följer mig"? I’m asking because Google Translate gives the second one as the translation of "He is following me", and the English Wiktionary gives the following example sentence : "En gatuhund följade mig hem." (without "efter")
They're essentially interchangeable. If I was forced to find a difference I would say "Han följer efter mig" might sound a bit more threatening, in the sense that you don't want him to follow you, but that's pedantics in my opinion.
For those who speak Dutch, is 'följer efter' the same as 'achtervolgen'? And just 'följer' would be 'volgen'?
how you say: follow after me, meaning behind nor with nor side..? följa bakom mig?
I'm not sure what you mean by "behind nor with nor side", but if you wanted someone to follow you and specifically stay behind you while doing so I would just completely rewrite the sentence to say "Håll dig bakom mig" ("Stay behind me") and let the following be implied by context, maybe after a simple "Följ mig" ("Follow me") if there is no context to imply following. There isn't really a neat, easy way to literally translate that sentence that comes to me right away.
eftersom du är cute och han är fancy you. :) awesome swedish sentence i know. :p