I suppose she's talking about net salary. Here is a histogram for France:

https://fr.statista.com/infographie/25111/distribution-des-s...

According to that, she's definitely in the top 20%. Of course "among the best paid people" is ambiguous depending on how much "top" you consider, but I think being in the top 20% it makes sense to say that.

PS: and I suppose (although it's hard to find data) that if we look at people in her age bracket, she will be in a higher percentile.