What is Job Grade 9 and who should come under this grade?

Is there any site or document which I can refer to understand job grades in Poland?

Are you sure it isn't a company's own internal grading system?

How many years work experience do you have, by the way?

I am not sure. It may or may not.

It is internal, I'm sure. Unless it refers to the number of years staź (years of work) you have. Why not mail them and ask?

Good luck with the new job.

Yes, you are right. I should ask them. Thanks for the advise.