CPU: a b c.   a=estimated cpu usage (system-wide) per second, b = cputime (app), c = gputime (app)
MEMORY: a b.  a=private mappings (app).  b=available memory (system)
FPS: a b.     a=main window framerate (foreground window).  b=display framerate
EVENTS: a b.  a=cumulative input events to the window.  b=cumulative input events on the display.
OBJECT:       nothing
API:          # of opengl calls (app)
DRAW:         # of draw calls (app)
TRIANGLE:     # of triangles (app)
VERTEX:       # of vertices (app)

CPU note: The CPU values represent percent of total CPU capacity so if you see "cpu 43 0 0", because it's a dual-core CPU, that could mean one CPU is running at 86% and the other is mostly idle.  

Generally seeing "cpu 50 0 0" would mean you've got one CPU "pegged" at 100%, so that may be a sign of a problem.