Upright
A milestone worth marking, and people to mark it with. The Four is stability that feels good rather than merely safe: a homecoming, a first real success, the point where a thing becomes somewhere you can stand.
Reversed
Reversed, the celebration usually got skipped, or the home isn't restful. It's worth asking what you achieved and never actually stopped for.
If this is your card this month
What have you accomplished without ever marking it?
A card is a prompt rather than a forecast. It doesn't know what will happen, and the useful part is what you do with the question it hands you. We make that case at more length in not a prediction, a mirror.