You forgot some important part of the quotes.
• Toopenthetoolboxbyright-clicking(Win)/[Ctrl]-click- ing (Mac), activate the “Popup Toolbox on Right Click” option in the Preferences dialog (Editing–Tools page). > When this option is activated, you need to press any modifier key and right-click (Win)/[Ctrl]-click (Mac) to open the context menu. When it is deactivated, you need to press a modifier key to open the toolbox instead of the context menu.
Basically the toolbox is something you can enable via your preferences.
Once this option is selected, when you right click, a toolbox will show rather than the context menu. Screenshot of the toolbox:
That allows you to easily select different tools, if for some crazy unexplained reason, you choose to select tools by mouse clicks rather than easy to use keyboard shortcuts
Furthermore, when that option is selected (right click for toolbox)…if you click and hold the right mouse button, after a second or two a crosshair will appear that will allow you to resize the toolbox. As shown in the screenshot above, it is one long row. You can resize it to be multiple rows.
Hope that helps.