This is the slice detail editor.

Use the up and down arrow keys to navigate the menu.

Click or press enter/space/left/right on a [Section] header to expand/collapse it.
Press Tab to expand/collapse all sections.

Use the left and right arrow keys to change values, or you can type in numbers.

Press F1 on the other menu items for more detail about each of them.

Press F4 to switch between hiding the menu background, the menu (so you can see the slice collection unobstructed), hiding the slices, or showing both.

Right-drag with the mouse or press F6 to pan your view of the whole slice collection. This does not modify the collection, it is only for help while editing.

Press F7 to toggle whether an outline box is drawn around the currently selected slice.

Press F8 to open the Slice Editor Settings menu, where you can access most of these functions, and more, without having to remember the hotkey for each.

Press V to toggle the slice visible/invisible. This doesn't work on the children of Select slices. Invisible slices have a different colour in the menu.

Press R to reset the slice's position: to position 0,0, aligned and anchored to top-left corner, and not filling.

Press F to focus on the slice, shifting the view of the slice tree (like F6) to put it near the screen center.