A matter of fact, in the Humean sense, is the type of knowledge that can be characterized as arising out of one's interaction with and experience in the external world (as compared to a Relation of Ideas). In a Kantian framework, it is equivalent to the synthetica posteriori.
-The sun will come out tomorrow. (Not reason but habitual)
-There are people outside the room. (One cannot know what is outside one's own experience)