In the RED circle you have a slider that you can move to go faster or slower. This affects the Time and Cost highlighted in blue (30 currently 30 minute estimate, transaction to be done within 3 blocks and fee of 0.0002 BCC)
In black you have the option of manually entering in exactly how much you want to spend on your transaction time, and your payment will be processed accordingly based on that fee.
This is an example for BITCOIN CASH wallet. With BITCOIN it's set up identically.
The link I gave you provided a far more technical and in-depth view of the transaction system. It specifically outlined how long you are expected to wait based on how much you pay.
Basically on the website, the far left is the amount of satoshi's you pay (1 satoshi = 0.00000001 btc, the lowest bitcoin payment possible) per byte of a transaction.
Since every transaction is approx. 230 byes, you basically multiply the number on the left column by 230 to see how long it will take to send the transaction.
Example: I want to spend 90 satoshi per byte because I want my payment to be complete between 30min - 1140min ( min - max range).
So it would cost me 90 * 230 = 20,700 satoshis (or 0.00020700 btc) to make this transaction happen, regardless if I send 1 btc or 2,000 btc.
This calculation is all done for you in the bitcoin wallet, the website just goes a bit more in depth to understand the impact of payment amount vs transaction times. It's also interesting to see how many people used which payment option for their transaction in the last 24 hours, very handy.
