The work area is represented by the blue bar running along the time ruler at the top of the layer view.
You can use the work area to specify a particular part of your composite shot to export, rather than exporting the entire timeline.
To set your composite shot work area, drag the grey tabs at the start and end of the blue work area bar. You can also press the I key or the O key on your keyboard to set the work area in and out points to your current playhead position, or use the In and Out buttons on the Viewer.
Exporting the work area
To export your selected work area, click either the Export button at the top of the composite shot timeline, or switch to the Export screen.
In the Timeline menu, ensure that the correct composite shot is selected and that the Export Area menu is set to Work Area. Only your chosen work area will be exported.
For information on the rest of the export settings, take a look at the Export section.
RECAP The work area is useful for exporting a specific section of your composite shot, rather than the entire timeline.