Walls: We see three different types of walls. Starting from the bottom left, we see a solid wall. Once we pass on the other side of the doorway, the wall takes a 90 degree left turn. When we see the wall again, it now has support structures on the outside of the wall.
The support structure on the wall is called a Counterfort
This indicates to me that the wall is not to keep people from the outside from coming in, but the occupants of the garden are being kept in. The supports are incorrect for protecting as you want the flat face of the wall towards the undesirable boogiemen. As the wall makes another 90 degree turn to the left, the wall has changed yet again. Now we see arches spaced in short intervals, whereas the previous section of wall showed no such arches. The wall is also comically short. Which is highlighted by the normal sized entrance arch.
This arch is pretty fancy, yet the door is just simple fence planking. The top of each shows a triangular cut. We can see they are simple pieces of wood. The door features three locks, which also are placed on the exterior side. This means that the occupants of the garden are locked in.
People: The gentleman waiting at the gate seems to be either contemplating the door or is waiting for an answer. The man seems to be oblivious to the short wall that could easily be scaled. This might be invisible to him, as perhaps his journey takes him through this wall. The man’s feet are not visible, I assume that it is from him sinking, perhaps again from a long wait. I am not sure what the turtle shell errant shirt sleeve is doing. He also is oblivious to the two crowds off to his right.
Next, we have the group of eunuchs sitting under the trees. They possess various instruments. We see a harp being possessed by the sketchy, devil-horned character. Yet, not as intimidating as the chimney sweep from Mary Poppins.
Above them sit four women who seem to be staring off in different directions. The women might have once been the inhabitants of the garden. I cannot ascertain any other meaning from either of these two groups.
Garden: So there is some sort of order in the garden, featuring planting boxes and well-defined walkways. We have the single small tree in the center. We also see a cluster of trees in the upper left. These trees appear to be planted in a row. As we look at the garden boxes, it appears there are the remnants of cut down trees in several of them.
Conclusion: I believe this might be a reference to being locked out of the garden of Eden or some variation of personal “Eden’s.” It appears to be a self-imposed exile as the wall can be scaled. The concept of waiting is apparent. We have nine people in the vicinity of the man, yet, no one seems to be moved to assist the man. I assume with the sinking feet he has been standing there for a while, and he might have become a spectacle.