Can someone please tell me in plain English what “ActivePoints Count” and “TotalPoints Count” mean or what they represent.
Thanks. 
ActivePoints is how many points are able to be sculpted at the moment. Normally, that is the number of points in the current SubTool, at its current subdivision level. If part of the SubTool is hidden then it’s the number of visible points.
TotalPoints is how many points exist in the entire model, across all SubTools at the highest subdivision levels.
Points are also known as vertices, in case you’re familiar with other 3d programs that use that terminology.
A ‘polygon’ is a closed 2d shape made out of straight lines (‘edges’). Because it has to be closed by definition, a polygon needs a minimum of 3 edges (which forms a triangle). Zbrush requires polygons to have only 3 or 4 edges. A ‘vertex’ or ‘point’ is the position where two or more edges connect with each other.
Basically a 3d model is a complex game of connect-the-dots. When you sculpt or do anything to edit a model (in zbrush or other programs), you’re directly working with those dots. Adding them, moving them, deleting them, connecting them to other points, etc.
Thanks aurick and Cryrid, I’ve been using Maya for the pass few years (just for personal stuff) and when you swap the word “Points” for the word “Vertices” I completely understand it now. 