With facebook accounts you can have unlimited followers,  but can only have 5000 friends. 

That's because an account is different from a page.

A page has some features that an account  doesn't have. 

Friends are different from followers,  though your friends are still your followers. 

In other for you to get unlimited followers on your facebook account, you will need to torn ON Professional mode on your facebook account. 

Once your account professional mode is activated,  your add friends button is Converted into a Follow button, when ever someone clicks the Follow button the  person becomes your follower.

But if the person clicks on the Add Friend button the person is requesting to become a friend not a follower but if you leave the Friend request unaccepted, the person remains as a follower,  which means if you keep accepting the friend requests it will arrive at a friends limit of 5000, but not stopping you from getting more followers. 

Even if your your friend  list reach it 5000 limit, you will see that you have 5000 followers,  and once a person click on the follow button you followers amount will increase to 5001 and so on. 

I hope this helps. 

If you have any more issues,  you can always submit them to  PROBOOSTA on facebook.