I am top 0.19% this week. What does this mean ?

Question

how the ranking is defined ? and on what basis?

Answer 1

It means you beat 99.81% of people this week in terms of xp gain.

Answer 2

The ranking is based on the XP you gained. The new week started today, so it seems that you've been hardworking in the last hours. You can see your rank and XP in the leaderboard compared to others in your country or worldwide.

I hope this answers your question!

PS: You can find the leaderboard by tapping on the 0,19% in your Activity Feed or the three dots in the upper right corner