Endoscopy done, multiple sessile polyps 3-6cm in size in entire stomach. does this require surgery? sessile mean cancer?

Just polyps: Sessile means fixed, with no stalk or directly attached to the mucosa. I am sure the gastroenterologist who performed the test took few biopsies, the results of which will answer your question.

Do U mean mm not cm?: Multiple diminutive to small sessile polyps of the stomach, as may often be seen with prolonged use of acid suppression therapy, are typically glandular & therefore of little clinical concern. However, if your multiple polyps are 3-6 centimeters in size, then they R very concerning--please check with your diagnosing physician as to the histology of these sizable lesions & his/her recommendations.