Metals are found in group 1, 2, and abit of 3.
Non-metals are found in group 0/8, abit in 4, 5, 6 and 7 too. Here is a picture. Most of the periodic table are metals.
Variable is a letter next to a number whether it’s x or y it can be any letter really but main ones is x and y and data is something written down from an oberservartion whether it’s an experiment or table etc.