Gameplay is what determines what a game is and how it works. Without gameplay the game would be boring and there would be nothing to do and the game would not become popular, it would also have no purpose.
This is at the top right of the bar at the top, there are accounts for both teams red and blue, when the team reachs a certain amount defined in the config of the server, the game is over and a screen will show telling which team won and how much each team player contributed to wining by displaying the amount they contributed next to their name. To add money to your team account you mine Gold and Diamond then bring that to the surface, each player can only hold a certain amount of Gold/Diamond which is dispayed as 'Weight' at the top of the screen, differant classes may have differant max capacity of Gold/Diamond that they can hold.
Blocks are used for many different reasons but the only block that is not used is the dirt block. The Ore Block is used for making blocks, the Gold Block is used to increase cash value of your team. The Diamond Block is also used to increase the cash value of your team.
(You can read more about the blocks in this section by clicking here)