The whole process consisted of 3 parts:
1. Language skills interview (in English);
2. Interview with HR department;
3. Professional skills interview (which also included some writing task to complete at home afterwards).
To proceed to the second step of the interview you have to pass the first one successfully. Every step was conducted by different interviewers and there was one person who coordinated me and arranged all the meetings. The last part was the most difficult and the most time-consuming, but there was enough time provided to complete everything.
All in all, I would say the interview was conducted in a friendly atmosphere so the stress was minimized.