The Use of the -f Flag in Permit to overcome the eventual Difficulty made from a Pre-existence of the same Symlink.
So if you want Simply make a Symlink without to Check if it Already Exists you Perform like:
ln -fs /path/To/Original /path/To/Symlink
To Get some Extra-Insight Look this other Guide:
HOW to Find Files/Directories/Images on Linux Command Line