I am an admin and can't figure out what are the two numbers (possibly Processing time and Data size) showing at right top corner in lightning UI (highlighted in the screen-shot). How do I remove those numbers ?
To answer your question directly, to turn these off:
Go to the setup menu, and search for "Lightning Components" in the Quick Find (Or the click path is Custom Code > Lightning Components with Lightning Experience turned on).
Make sure that the "Enable Debug Mode" is checked off, and save.
You may have to refresh your browser cache, but those two components should now be gone from your Lightning Experience UI.
Now to the interesting questions of what they are. Doing a little DOM spelunking and using the wonderful Lightning Inspector reveals that the left-most is a Lightning Component in the One Namespace called "EPT". The other is a Lightning Component in the auraStorage namespace called "FuelGauge".
Since aura is open source, you can check out what FuelGauge is doing here.
EPT is a bit more tricky, and my best guess is that it is doing some performance monitoring in terms of page load.