The labia majora are folds of skin on either side of the urethra (urinary opening) and vaginal opening. There is thus one on the left (the left labium majus) and one on the right (the right labium majus). The plural for labium majus is labia majora. Thus, the urethra and the vaginal opening lie between the left labium majus and the right labium majus. The following site on the internet will show you a picture of the labia: www.gynaeonline.com/images/female-an.jpg
In general, lumps in the breast should be removed, regardless of size. Note that your idea of a lump may not be the same as your surgeon’s idea of a lump,; therefore I cannot definitely say that your lump needs removal. However, if you are dissatisfied with your surgeon’s opinion, consult another.