Is “sales” singular or plural?

Which of these sentences is correct?

1. What does sales have to do with copywriting?

2. What do sales have to do with copywriting?

Because Merriam-Webster doesn’t specify whether “sales” is singular or plural, I turned to my colleague Paul Stregevsky for guidance.

Paul says that #2 (where “sales” is treated as plural) is correct. That’s because “sales” is the semantic subject.

Semantic who?

Apparently, there’s a distinction between “semantics” and “syntactics.” (I’d never heard of this either.)

Happily, Paul explains by way of examples:

Here’s a syntactic subject:

“Sales is a dwindling occupation.”

And here’s a semantic subject:

“Sales are climbing.”

Thus:

“What does sales have to do with copywriting?”