Zendesk WFM wants to bridge the gap between an agent's work, how it gets reported, and then how it loops back into their performance assessment.
Performance boards in Zendesk WFM are a way of giving agents going about their work visibility over certain key metrics that are important to them.
Setting up a board allows a manager or admin (or someone with the Permission to do it) to choose from a set of reporting metrics, set goals for each metric, and apply them to a team. Then, you have the option to make that board visible to agents, and in turn those agents will be able to see how they performing as they work - right there in their WFM schedule in Zendesk Support.
There is also an optional Leaderboard feature if you want to foster some friendly competition.