When you watch a game you can guess both player's moves by making a move on the board.
When a lot of people are watching a GM game sometimes it's fun and after the game people can see who guessed the most.
1/7 means someone watching your game guessed 7 times and was right 1 time.
Since you're not a famous GM it was probably one of your friends (or a friend of your opponent) watching.
I just played a friendly game, non tourney, when the game finished a dialogue in the chat section appeared, with someone's name and it said in blue "top guessers, 1/7"
What does it mean?