Offset specifies the distance between your design and the cut path. This is a very important tool for fine-tuning fitment between two objects, or when creating roughing and finishing passes when cutting.
You can define positive offsets — those that go inside of the design — or negative ones — that go outside of the design. Tapping +/- allows you to toggle whether an offset goes inside or outside of your design.
You'll see a variety of presets to the left of the keypad that allow quick access to common offsets. Tapping any of these will immediately apply the new offset.
Using the keypad will allow you to precisely specify the offset.
Tap DONE on the keypad when you're ready to apply the new value. Origin shows the offset visually as an offset between the design and the cut path.
Note: Cuts encoded as On Line or Guide cannot be offset because those cut types do not have an 'inside' or 'outside' that Origin can recognize.
With offsets, you can easily cut multiple roughing passes (with a positive or negative offset) followed by a single finishing pass (with a zero offset). This will keep your cuts clean and accurate and ensure tight, reliable fits between pieces.
For more information on cut offsets and how they can help you improve cut quality, see these videos on finishing passes and using offsets for perfect fitment.