Answer 1

it means you have earned a lot of xp in the specific week.. there is only an amount of 0.02% solo learners who have gained that much. so you are one of them!
If the percentage confuse you here is an example;
Think that there are 10,000 sololearners in your country. the percentage defines that there are 2 people out of 10,000 who’ve earned highest xp rates. In other words there are 2 winners in the 1st place. So as it is obvious to put two names in the 1st rank, they mention it as a percentage.

Answer 2

So if there are 4 million Sololearners, it may mean that your XP for the week are amongst that of the top 800 learners.

Answer 3

This mean... you are part of 0.02% people who gained this much...xp..from your country 😊

Answer 4

It means the xp that you've gained this week puts you in the top 0.02% of all sololearners 😊