A Focus palette is a reference to a specific area on stage. When presets are recorded with moving lights using Focus palettes, they do not record the absolute positions of the fixtures; they reference the Pan and Tilt parameters of a Focus palette. If that palette then is updated to reflect a different position, those presets will point the moving lights to the new position.
For example, thirty presets may be recorded with four moving lights pointed at the drum kit. Each preset references the Focus palette for the drum kit. If the drum kit is moved somewhere else on stage, all that the programmer has to do is update the Focus palette to the new position, and then when the affected presets are recalled, they'll reference the updated position of the Focus palette.
To record the focus palette in the above screenshot, a programmer would select the four devices, point them at the drum kit as shown, then press [RECORD]&[FOCUS], opening a dialog box asking for the name of palette and how the attributes should be recorded; in this case, [Each Device]1 is the desired option.
The behavior for the palette will be as follows:
1The differences when creating palettes to record attributes for [Each Device] versus [Each Device Type] are explained here.