HistoryLink Summary Section

Total Profiles is the number of Geni profiles that were searched.
Total Matches is the number that matched a Geni Project.
Master Profiles is the number from the Total that were Master Profiles
Pending Merges is the number of profiles that have a Pending Merge
Parent Conflicts is the number of profiles that have a Parent Conflict.

Tree Completeness is a graph for your direct ancestors
Total Per Gen is the measure of that generation - so you have 4 grandparents - 100% would mean you have profiles for all 4 grandparents. 3 grandparents would be 75% (3/4).
Total All Gen is direct Ancestors to that point, so 4 grandparents + 2 parents = 6. This value is then converted to a percentage for the possible total. So if you only had 3 grandparents, this value would be 83% (5/6).
MP Per Gen is the number of Master Profiles in that Generation, represented as a percentage.