What causes tingling and numbness on right arm?

Depends .. It could be from multiple sources. It could be related to compression of nerves stemming from the neck, armpit(axilla), elbow or (less likely) the wrist area. It could be a toxic/nutritional deficit effect on the sensory nerves, though this tends to affect both sides. It could be from a particular issue within a sensory area of the brain(exceptionally unlikely). .