I am currently creating a low poly rock, however there seem to be more edges than I can edit. Could someone kindly explain how I did this?
You added a Subsurf modifier on top of problematic geometry: simple as that.
Subsurf works best with quads (polygons with four corner vertices), as it splits every quad into four new internal quads. It will also work on triangles, as it splits those into four new internal triangles.
You, however, use Subsurf on so-called “n-gons” (polygons with more than four vertices) - and non planar ones on top of it. Those are notoriously hard to handle for Subsurf algorithms and this leads to those unpredictable results you see in your screenshot.
Thanks a lot for the explanation. I appreciate your time!