/etc/fstab is your mount options, these are what are mounted automatically at boot, what you have shown is the root filesystem “/” and the UUID of the physical hard drive/ssd that goes with it.
fstab is different than a symbolic link, a symbolic link is more like a shortcut if using the -s option.
Are you trying to make a folder in /home/ called MyThings that goes to the external drive? then what you should have is ln -s /run/media/robafovio/TOSHIBA EXT/ /home/robafovio/MyThings
The one thing i am unsure of is if you remove the drive how the symbolic link works when you later plug the drive back in. As in, if it will just keep working in the future.
what do you see when you run the command below? for me my external doesn’t show a name like yours it’s a long string of numbers and letters, but if it does say TOSHIBA EXT then Jonathon is correct due to the space you need to do what he said.