Rating: ranges from 0 to 100; goes up every time you answer correctly and goes down every time you answer wrong.
Ranking: ranges from 100% to 1%; shows how your skills stack up to those of other users of SNG Coach. A ranking of 1% means that you're among the top 1%, i.e. more skilled than the other 99%.
Place: the Top 20 players get to see their overall place in the global leaderboard.