Hello and welcome to the forum. Thanks for your question. Normally after a biopsy, a doctor will go over results with the patient. Have you had this appointment yet? If you haven't, please ask them to interpret the results in a way that you understand. If you have, you can call the office and say you'd like the results explained again because you are not sure what they mean.
Basically though, we'll try to help until then. An endometrial polyp is a growth in the uterine cavity and they are fairly common. Very few of them are cancerous.
Why did you have the biopsy done? Do you have endometrial hyperplasia? Here's more information on uterine or endometrial polyps.