The hexagonal symbol in the highlighted area identifies a splice point in the harness while the triangle symbol shows the ground point. A splice point directly connects two or more wires without using a connector (e.g. a soldered joint).
(B7) and (E1) are splice point codes used to identify their location on the vehicle.
A ground point connects the circuit wiring to the vehicle body or engine unit. (BH) and (EB) are ground point codes used to identify their location on the vehicle.