This is good advice. Interactions between people usually have loose scripts, but are mostly improv, and a big part of that is encouraging the other person to keep talking about what they are interested in. The hard part for me is usually when I find I don't have much to add, but usually I try to agree and paraphrase what they've said. This shows you're genuinely paying attention and care about what they have to say, and invites them to clarify or keep going. Really, just try to find things in what others say that you can agree with in general and you'll likely be in a pretty good spot.