What does it mean when you wrote your but and see blood?

See your doctor. It means you need to have a proper examination by a doctor. A colorectal surgeon will take a history and do a specialty exam of the anorectal area. Please make arrangements to be seen: bleeding is not normaal and should always be evaluated.
Likely hemorrhoids. The most likely cause is hemorrhoids, but in rare cases this is how cancer can appear. Visit your doctor to continue your evaluation.