It contains buttons and menus that provide quick access to commonly used commands. It is a

A bar of buttons and menus giving quick access to common commands is a toolbar.

A menu bar lists menu names but not the quick-access buttons described here.

A window is the framed area that shows a program, not a bar of commands.

None-of-these does not apply, since a toolbar fits the description.

Toolbars often sit just below the menu bar in a program.

Hovering over a toolbar button usually shows its name as a tooltip.