Ask HN: IT industry book for an idiot?

I'm currently working as a recruiter at a firm that dispatches engineers (IT, design, mechanical, etc.) in Japan. In the nature of Japanese companies, I'm going to be moved from this position into an area in which I have next to 0 experience. From July I will be the main sales person for our IT clients. I would like to say I have more knowledge than Joe Blow about the industry, and I also live in the 21st century/read hacker news. I'm looking for a book/website that would give me some general information about different languages and what they're used for/what other languages they're related to so I don't look like a complete idiot when talking to our clients. Anything would help.