When something is easy or not complicated, not time consuming or an inconvenience.
Likewise,
When something is explained to you and you are expressing that you have understood what has been said and it is now easy for you to understand.
Its as simple as a click.
Scenario 1
Person 1 "Hey, could you please drop me off at the shop later"
Person 2 "Yeah, it's click'
Scenario 2
Person 1 "...and so thats how you do it"
Person 2 "That's Click! Thank you so much"