Basic knowledge of English?
Can I say she has basic knowledge of English?
Or her English is at basic level?

Question

Answer

Both are correct but the Grammer needs one more word in there.

Here English is at 'a' basic level

Answer

"She knows a little English, ...not much. She's a beginner. "

Answer

Her English is at a basic level. 
She has basic knowledge of English.

Both work.

Answer

u can say -she has basic knowledge of english :)

Answer

Her English is at a basic level.