3 Steps: Technical interview, human resources interview, manager interview.
1) how is made an invoice, main its characteristics. if and how my cv may fit with the position. Some question about simple command of Excel and how was my level of Office in general
2) "classic" interview: my 3 strengths and my 3 weaknesses. How would I feel myself in a multicultural environment.
3) where would I see myself in 3/5 years.