I play Starcraft and today someone asked me if I had ever played 'ranked'.
What does that mean?
That person was asking you if you have ever played against other people for a place in a leaderboard. Starcarft 2 has a ladder system. You get into leagues and you increase your rank by winning matches, or decrease it by losing them. Think of it as a permanent tournament going on.
If you perform well you are promoted to a higher league. If you don't, you are demoted. There are 7 leagues per each mode.
With modes like 1vs1, 2vs2, and so on. Grandmaster is 1vs1 only though.