Associate of the Royal Conservatory of Toronto. It's the highest level the Royal Conservatory gives out.
I personally don't believe it means you can basically play anything. I don't think passing any grade necessarily equates to being able to play anything at that level. I do believe once you get to that level you can probably work anything out, but being able to play something and the effort required will vary amongst people even when you get to that level.
I can play lots of stuff reasonably well at higher grades while I struggle with some stuff at lower grades. It's just a case of what is natural to us (and what we like to practice) and what is less natural. However, anyone that gets to that level has more than enough skills to work most stuff out. How esaily it comes to them is another question entirely.
Check out the RCM Examinations
website for more information. Unfortunately, unlike some boards, the RC dislikes having people be able to see their play lists for the grades without buying their books.
However, you can check out the British Columbia Conservatory of Music
for some syllabi lists of similar pieces and their grades and pieces align very well with the Royal Conservatory's.