I have wrist pain when I type. Could this be serious?

No. Serous? If it's your wrist and it hurts a lot, that may be serious enough for you to change posture, position; take rest intervals; stretch; possibly use anti-inflammatories like ibuprofen. Wrist splints/wraps are simple and may help too.
Not likely. Pain when you type is not likely to be something bad or scary. It may be as simple as just needing to take a break and stretch your wrist and fingers. Joints don't like to be stuck in one position for too long. If your pain seems severe or you have other problems with it such as numbness or tingling, maybe you have carpal tunnel syndrome. Don't worry, that's easily treated, too. See your dr.