Anterior mesenteric side" what does it mean?

Anterior = in front: The mesentery is a continuous set of tissues which is formed by the double fold of peritoneum ... The colonic component of the splenic flexure occurs lateral to the mesenteric confluence. At every flexure, a continuous ... to the posterior abdominal wall. The descending colon occupies a similar position on the left side. Ref: https://en.wikipedia.org/wiki/Mesentery