The Commander feature has not yet been released for general use - details of what to expect are listed in items on the "News" page.
This page will be updated in due course.
When Commander is released it will let you quickly execute various browsing actions without having to remember or press awkward key combinations.
It will act as a universal search bar for all browser shortcuts, menus, settings, and more.
To access the Commander you will need to enable the appropriate feature flag.
To do so enter chrome://flags/ in the address bar, and then search for Commander. Once located enable its flag and relaunch Chrome.
To activate the new search facility hold down the Ctrl key and press the spacebar which will cause a small pop-up search bar to open up.