When a detection is considered a "false positive", that in itself isn't necessarily an indication of the safety of the object for which the detection is concerned; Simply put, a "false positive" indicates that the specific string, data, behaviour, detection method or whatever else is being used to trigger the detection is present in the object that has been detected, but that the object was not an intended target for that detection.
As an example.. Imagine that you are in control of a medium of communication and you are wanting to prevent the users of that medium of communication from using it for the purposes of torrenting. You notice, over the course of some time, that most of these users include messages such as "check out this awesome new torrent!" with every torrent file that they upload, and so, as a means of assisting with the prevention of these activities, you decide to write some script, program or policy to execute alongside this medium, to automatically detect and block any communications that contain the string "torrent".
This would mean that every time someone uploads a torrent file and includes the aforementioned message, it is detected and blocked, because of the message containing the word (or string) "torrent" contained therein ("check out this awesome new torrent!"). You'd consider this a successful, positive detection.
Now imagine that one day, someone writes and sends a blog post through this medium of communication that briefly has some mention of torrenting in it, and due to that mention, also happens to contain the word (or string) "torrent"; The specific post doesn't contain an attached torrent file and is not intended by the original author for torrenting, but nonetheless, due to this script, program or policy that you'd have written earlier, their blog post is detected as an attempt to use this medium of communication for the purposes of torrenting. You'd consider this to be a false positive.
If your anti-virus solution, whatever else you're using or wherever else you're reading about false positives is telling you that something is a false positive, what is meant by that, simply, is that the object or thing being detected is not what the specific detection was intended to detect.
In other words.. The object or thing being detected may or may not necessarily still be dangerous.