A Practice Leader is the first point of contact for their direct reports, and they liaise and relay information between senior leaders, HR, and engineers.
The role of a Practice Leader is probably the most important because this is the first line of people management, and it provides things to be done. On the one hand, a PL is a part of the Practice, so this person must be at least senior-level in their specialty. On the other hand, a Practice Leader is a people manager.