This is the currently negotiated operational speed of this internal port channel. Because internal FI-to-IOM links auto-negotiate and the channel's effective bandwidth is the sum of its up members at this speed, a lower-than-expected operSpeed here (say, half the rated line rate) is a direct signal that some member ports are down or negotiated incorrectly, well before any traffic-drop symptom shows up elsewhere. If the chassis is rated for 4x10G but operSpeed reports the equivalent of only 2 active 10G members, that's the channel silently running at half capacity.