This means I don't have a single question, it means I want to have a synchronous conversation. There are lots of reasons for the latter. This is what I would prefer people do with me as well, and if I am busy, I feel like I can ignore the message until I have a few minutes to talk (often with voice/phone)
I say this as someone working from home, thousands of miles from most people I work with and also far from most people I communicate with socially online (such as family). I find this approach of "just send a question and they can answer asynchronously" to be one of the reasons that working from home can be damaging to mental health. Natural human interactions, where there can be a real time back and forth, are positive things. Not necessarily always, but especially if I haven't communicated with a person in weeks, I'd much prefer this sort of thing.
If there is a specific topic I want to talk about, that can be expressed in a few words, sure, I'll say that. And if it really is just a simple question that can be answered directly, I'll just ask. But the point is that those are not always the case, and depending on the job each of us has and our relationship, it might be unlikely for that to be the case.