As I understood it, ShareAll links people lending stuff with people wanting to lend stuff. You can replace stuff with any kind of object you could share. They use a virtual currency to make this possible, named "Shares".
For example:
If I wanted to use their system and say use the landmower of one of their members, I would buy some "Shares" with real money, or lend something I own to earn some "Shares". I can then use those "Shares" to use the landmower for one day.
Everytime you use those shares, so when you buy them, earn them, or when you use them, they take a little part of them (= a transaction fee). That's how they make money.