You must buy all your supplies, manage your tractors and other machinery, keep up with the price of grain and, ultimately, worry about almost everything that a real farmer has to deal with.
The graphics are quite simple, and while they don't do anything fantastic, they do what they have to. The game more than makes up for it with the sheer range of management options that are made available.
Modern Farm is a really comprehensive game that requires high levels of skill and patience on the part of the player. It does however provide some pleasing rewards for your efforts.