Anyone remember that classic children's book? The story of a little bird falling from the nest and wandering around asking everyone and everything, "Are you my mother?". Well eventually that little bird does find its mother, so don't worry!!
So what does this have to do with Revit? Sorry!
Occasionally you get a family, say a truss, load it in a project and then you wonder...what kind of family was it? It is probably a structural family but which type? So the simplest thing to do at this point is just open the family in Revit. Once open, click Settings > Family Category and Parameters.
Then notice the category selected.
That's assuming of course that you haven't already placed the family. If you did then it is easier still...just hover your mouse over the object, take a look at the status bar or the tool tip that appears.