The windshield wipers are loose. Sometimes the blades go too far left or right. I suspect a bad bushing or gear problem with the motor.
The mounting joint for the wiper blades often comes loose on a vehicle allowing the blades to come "off track". In many cases, the connection can just be tightened. In other cases, the wiper transmission assembly may have broken. I recommend having an experienced technician inspect the system and determine the cause of your wiper problem.