From The Document Foundation Wiki
- Send to the front: Places the selected object above any other image or text.
- 'Send forward: Places the selected object one level higher in the stack. Depending on the number of overlapping objects, it will be necessary to click several times on this icon to obtain the desired result.
- 'Send backwards: Moves the selected object one level lower in the stack of objects.
- 'Send to the back: Moves the object selected at the very bottom of the stack so that the other objects or the text covers it.
- 'In the foreground: Places the selected object in front of the text.
- 'In the background: Places the selected object behind the text.