This is a module that helps to keep information about various things that exist in a company (like book, computing hardware etc.) If installed, you can reach this module via mytutos/search/inventory.
To define a new inventory item you will need only a name. A unique id is also neccessary but will be defined by TUTOS if you keep the "auto" number. The rule how those auto numbers are replaced could be changed by the admin in the stuff config page.
or more detailed/specific
For example type "amazon" in the source field and TUTOS will show you all inventory items you got from this source.