Some companies conduct several rounds of interviews. They can be of different types in order to assess as accurately as possible how suitable you are for the company. This is also done so that the candidate appreciates the position he receives; you will not want to leave after a year the job that you got with such difficulty. Don't worry if you don't know what to talk about or what questions to ask your interviewer, there is a lot of information on this topic here https://www.gotresumebuilder.com/job-interview-guide/researching-the-company-and-questions-to-ask-the-interviewer . The purpose of the interview is to understand your fit for the position, so try to include specific examples in your answers about how you can benefit the company, why you are the right candidate, and how your experience will help the company move forward.