Engineers should always be working to learn new skills to make themselves more valuable. Being willing to learn on your own time is the mark of a truly valuable employee who will help the firm grow and bring in new clients. If you have picked up new skills, this is your chance to brag about them, and explain why you think they'll add value to a new firm. If not, don't worry -- use the time answering this question to discuss something you are interested in learning about.