Fence: a barrier. In baseball it marks the delineation between a hit, or out, and a score: a home run. As in sports, in the larger sense, it represents the barrier between being on the team and actually playing. The play represents a period in time during which barriers (fences) are being broken down. But supposed that you grew up surrounded with them? How would you react? Troy, the ex-ballplayer, is trying to build a fence; he wants his young son to help, rather than to become a part of the change.
This is a masterpiece. I will be looking for other plays/works from August Wilson immediately. Highly recommended!