Hi there, i have a simple question about the unit of area which found by polyline. the unit is square cm but i want to make it show as square meters, thanks

AutoCAD drawing is unitless, you start thinking in units when you dimension it, or when you define paperspace (layouts) or plot it. So draw in meters and you will get all reading in meters. You can also use fiields for creating area labels and include a conversion factor there. See also our fArea utility.