Hello Asocial,

the little tilde ~ symbol you see next to your rating indicates that your rating is still provisional, which means you haven’t yet played enough games for the system to calculate a fully stable score.
Once you played twenty matches, the tilde disappears and your rating becomes an established one.

If you’d like more information about how the rating system works, you can find it here:  

https://www.flyordie.com/games/help/rating_system.html