"When entering an electrical engineering interview, be prepared to answer a lot of technical questions that will evaluate your problem-solving skills and fundamental understanding of engineering and physics. The precise questions you will be asked will depend heavily on the type of role you're applying for, so make sure to familiarize yourself with the company and its line of work ahead of time. To ace your interview, come ready to tackle behavioral questions your ability to excel on a team and manage difficult projects."
Know the FPGA and VHDL programming process. It is like studying your subjects back in school because they want to know characteristics, types, process (block diagrams), and more like test questions during school time.
What are the process and types when programming FPGA? You should be reading the book again about FPGA.