This terms are very much known if you are using bitcoin in your daily life or you are playing a little with bitcoin. These are not much important if you are an end user who only spending bitcoin for daily life but if you are a bit interested how things going on- you must have those knowledge.
In the above image, imagine, you have received total of 1 BTC from Bob. Bob once sent you 0.30 BTC and later sent 0.7 BTC. Now, you want to send 0.4 BTC to one of your friend, from where you are taking the BTC? Bob's output, isn't it? So, Bob's output is your input when you are sending 0.4 BTC to your friend.
Here, we have used the both of Bob's Output.Input- Bob's Output = From where the BTC came from.
Output- Where BTC is heading to.
If you have a closer look at the above image, it will be clear to you.
In the above image, you have 1 BTC which Bob has sent to you. Now, you want to send 0.4 BTC to your friend. If you want, you can use one of the output of Bob- 0.7 BTC and this can be done through coin control, so, coin control is giving us the power to which output of Bob we want to spend. Now, since you will send 0.4 BTC from 0.7 BTC, you have some changes, right? Because you can't deduct 0.4 BTC from your 0.7 BTC input. Imagine, you have one single note of $70. You have purchased something worth of $40, now the shopkeeper will give you a change of $30.
In this case, you are telling like- I am giving 0.70 BTC, from where 0.40 BTC will be sent to my friend and the rest will be sent to my address (This address is your change address.)
I guess I have not done any mistake or used any misconception, If I have used, you can correct me. I always try to write something in a very easy way so that, a very newbie can learn something from my article.