The input is the frequency that the radio talks to the repeater on, The out put it was the other radios hear the first radio (Through the repeater) on.
It is the ingoing frequency for a repeater. You really only need to monitor the output. A good thing to monitor for inputs is police repeaters. Put the input right before the output on the scanner with no delay. If a police car is close to you, you'll know it.
so say 154.950 is the main freq and the input is 152.7. I could program the repeater in the same bank. Would I have to put them in order? Or would it matter.