Yes, you got it exactly! The Normal Map node is just a converter so that Cycles or EEVEE can read all of the normal related info in the same format in the shader. The menu on the node defines what space the input map is read in (tangent space, object space, world space, etc.), and once in the same format you can combine any type of normal map together. The other types are far less common these days but can still be helpful on rare occasions.
