At least in programming, syntax is structure. A structure can have substructures. If the whole structure has a different meaning than each substructure on its own, then syntax has meaning. Vise-versa, how could you tell the structure of something that doesn't have any meaning to you? How do you know the meaning of a word without knowing the grammar and context? The context is the perspective.

I didn't come up with syntax semantics duality myself and I can't really explain it, because it's actually rather mathematical.