A meaningful sentence is a logical picture of a possible fact

Wittgenstein's picture theory holds that a proposition means something because its internal structure mirrors a possible arrangement of objects in the world, the way a map's layout mirrors the layout of a territory without literally resembling it. What makes a sentence meaningful isn't that its words physically look like what they describe, but that the logical relationships between its parts correspond to logical relationships between possible facts. This is why we can understand a sentence describing a situation that has never actually occurred: we grasp the logical form being pictured even when the corresponding arrangement of the world doesn't obtain. A sentence's truth or falsity is then simply a matter of whether the actual world matches the arrangement the sentence pictures.

Takeaway: A sentence works like a diagram of a possible situation, true if reality matches the diagram, false if it doesn't.