To me all of these are correct.
1 I don’t know what advantages in knowing English are.
2 I don’t know what advantages in knowing English are good.
3 I don’t know what advantages are in knowing English.
4 I don’t know what the advantages are in knowing English.
5 I don’t know what advantages in knowing English she likes are.
But I doubt that all of them are correct in reality. What's your take?