/home/osmc/.kodi/userdata/
~ always indicates the home folder (/home/osmc/) of the user you are logged in as. The . preceding .kodi makes it a hidden folder. Just cd .kodi or if you are using some ftp client you may have to find some option that allows viewing hidden folders.
Here is a cheatsheet and some tutorials for how to navigate in a Linux shell: Cheatsheets and Tutorials for users new to Linux based operating systems