The three Gnumeric toolbars can either be hidden from view or shown above or below the cell grid area. The three different toolbars are explained in Section 4.4 ― Toolbars.
Toolbars can be hidden or shown by clicking with the primary mouse button on the View menu, the dragging the pointer down to the Toolbars to open its submenu and then moving the pointer into the sub-menu listing the three toolbars. By default each toolbar appears with a small check mark in front of its name indicating that it is visible. Clicking on any of the toolbars will alter its setting, making the toolbar visible if it is hidden or hiding the toolbar if it is visible.