What does Ch-Ch isolation stand for regarding this context?
I don't understand what meant by channel to channel isolation here


"Isolation" means that a signal on channel 1 won't appear on the trace for channel 2 or vice versa. It doesn't mean that the signal input connections for channel 1 and channel 2 are isolated (although on some equipment this may be so).

An isolation of 100:1 likely means that a 1 volt signal on channel 1 might produce a 10 mV signal on the trace of channel 2.