When a dove is sitting on the ground and not moving, it is typically a sign that the dove is either resting or incubating eggs. Doves are ground-nesting birds, so they will often build their nests on the ground in a sheltered area. When a dove is incubating eggs, it will sit on the nest for long periods of time, sometimes for up to 24 hours at a time. During this time, the dove will not move very much, as it needs to keep the eggs warm and protected.
In some cases, a dove sitting on the ground and not moving may also be a sign that the dove is sick or injured. If you see a dove that is not moving and appears to be in distress, it is important to contact a wildlife rehabilitator for assistance. Doves are very delicate birds, so it is important to handle them with care if you need to move them.