For entry level positions engineering positions, they dont expect you to know everything. You will be evaluated in your problem solving skills. If you have the essentials skills in the programming language required in job deion, a good fit to the team and motivated to learn the skills, thats what hiring team looks at.
Expect to have an interactive interview where you would be required to use the whiteboard. For example if your position requires C programming, you will probably be asked about memory allocations, using pointer in functions/structures etc etc.
Remember that the person interviewing is in the team you most likely you will be working with. So they want to see whether you fit in the team or not. Dont let the interview be you answering all the questions. You should ask lot of questions to the person interviewing, about job, skills you can learn down the road, career growth, team etc etc.
If you dont understand or they ask something you dont know, at least make an attempt to answer and ask for clarifications which will help you solve the question. Put an impression that if you dont know something, you can figure it out.
First round interview are tough. Since you have already cracked it you are in a great position. Be confident and good luck.