Please, next time post this is a more cocsise yet understandable way. Copy/paste prompt-command line, output lines and new prompt line between CODE tags (the # button above the post editor. That would have looked like:
boven:~ # zypper -root /srv/suse ar http://download.opensuse.org/distribution/leap/15.2/repo/oss/ OSS
The flag o is not known.
boven:~ #
When we can see exactly what you see helps enormous in understanding what your case is.