I've six fingers in my hand, can I get a better hand through plastic surgery?

Extra finger. It is possible to remove an extra finger on your hand. It is important to have your hand evaluated by an experienced hand surgeon. This will include imaging studies as well as a thorough history and physical examination.
Yes. This is a very common procedure done by well-trained plastic surgeons. The options for correction should be discussed with an plastic surgeon or ortopedic surgeon with special interest in reconstructive hand surgery. Be well.
Polydactyly Surgery. If your extra finger is fuctional and developed including an extra metacarpal (hand bone) surgery is more difficult and may not give you a "better" hand. If your extra finger is a small nonfunctioning extra digit by you pinky finger, the surgery to remove it is not as involved and will probably give you a "better" hand. This is especially true if your extra finger just gets in the way.
What is better? Some extra fingers are functional, others are just extra appendages. Depending upon appearance, hand surgery may improve function and/or appearance. Consult a hand surgeon to evaluate your options.