[DonRotolo]

I don't "know" but can guess with confidence:

Response time is latency: How long in time between the sensor sensing the condition to turn it on (or off) and when the signal actually turns on (or off). Propagation delay might be another word, depends on your field.

Repeatability is jitter: The time difference you might see from one 'event' to the next.

An engineer might write this as "750 uS +/- 50 uS for ON in Opposed Mode". For example. Maybe they mean +100, or -100, or even +/-100, can't say for sure. But I'm guessing +/- 50 is what they were trying to say.