The svn command 'switch' is issued to perform a RS version upgrade. The {version} you enter is the RS version to which you want to upgrade (no brackets). The good news is you don't need to know the current RS version to do this.
You may need to upgrade Subversion.
I'm no subversion expert, and won't guarantee a good outcome :-)
All that said:
Backup, backup, backup! -- especially the database and filestore folder. Make sure you have all site files backed up, especially include/config.php which may have specific customizations implemented.
My current install shows this in Installation Check: ResourceSpace | version SVN 9.2. Tells me it's a Subversion upgrade to ResourceSpace version 9.2. I know this was an upgrade from RS 8.6.
Hope this helps -- it's not much. I know enough to be a little dangerous. . .