In the top bar of ZBrush (using 4R7) there is a MeshCount value. For some reason, in my document this value is 2 and I have no idea why, what it means and how to change it. I have searched the documentation and found no explanation for this.
Thanks Doug Jones for your valuable feedback.
In case this thread interests other beginners, MeshCount is the number of subtools in the current tool. Strangely I didn’t find it in the docs when doing a search on MeshCount, or when looking at the doc on the header bar in the reference guide.
YW, the ‘information’ could be more readily displayed but it isn’t currently being done that way. 
Hold Shift and Ctrl over the buttons for Pop up information. My UI and files may be helpful to you. Happy ZBrushing.
Holding shift and ctrl or either of them when hovering on MeshCount is not doing anything, at least on Mac. Hovering with crtl on palettes works but not on the header bars.
Hmm. You will have to read some to become familiar with the capabilities of the software. ZBrush is a different kind of animal
http://docs.pixologic.com/?s=Mesh+Count
In case this thread interests other beginners, MeshCount is the number of subtools in the current tool.
The number of visible subtools