When finding software on the software.opensuse page, for example unetbootin, there are several options listed here (see image), what do they mean and wich one should I get ?
Are those some kind of repositories ?
Since all are the same version, I would go for the one from the “filesystems” repo. That repo is kind of “official” since it is a development repo for Factory.
Are those some kind of repositories ?
Yes.
Those home: repos are different people’s private repos, everybody can have such a repo and build stuff in there.
As wolfi said, these are all repos but the home: ones are peoples private repos and that means they can share software with other users. Generally I think it is best to not use the home: ones if there is an ‘official’ choice available. Only real exception to that would be if the software dev themselves host a repo and you want to get the program right from their repo.