This indicates the physical interface type this port implements (for example an aggregated port-channel member versus a discrete physical link). For this chassis slot's endpoint for whatever blade currently occupies it, ifType tells a monitoring system whether to expect this row's port/aggrPort values to describe a standalone physical link or one member of a bundled port-channel, which changes how you'd interpret a single port going down. A value of 'physical' here means this port's own up/down state directly reflects link health, rather than being masked by other members of an aggregate.