This test is called a Fecal Immunochemical Test (FIT). It is used yearly as a screening test for colon cancer. It does not directly detect cancer, but checks for another indicator sometimes called a biomarker. The screening is intended to detect problems early so they can be treated before they become serious.
In this case, the test detects hidden blood in the stool (poop) that may not be visible to the naked eye. Blood in the stool can indicate the presence of precancerous growths or colon cancer. However, pre-cancerous growth or cancers do not always bleed, so the test could miss them (a false negative result). Other benign (non-cancerous) conditions of the digestive tract, like hemorrhoids, can also cause blood in the stool (a false positive result).

Please note: This test does NOT determine if you have colon cancer. If you have a positive result you should see your doctor. You may require further testing, such as a colonoscopy.