It is a management simulation.
You are the manager of a club.
You have full reign over playing matters, through training, formation, tactics, substitutions, transfer negotiations, scouting, wage negotiations, interacting with the players, board, fans and media.
You go through tthe season day by day ( or hour by hour sometimes) performing managerial activities and dealing with th e"reality" of the game. there is an interactive ticker which communicates the actions of the players, managers, teams, media that are a part of the game.
On gameday you choose your squad and system and watch the game as it unfolds, You can make changes to formation, player runs, player focus 9attacking, defending), team style etc. throughout the game to effect a win or cause a loss.
One of the best parts of the game and the most time-consuming is the detail of the database. You can easily spend hours checking out potential transfer targets, youth team players, scouting reports etc. because the database is very detailed.
Also you can apply for ( or will be recruited for) available jobs withinn the game environment.
For example if youstart with Stockport in th elower division you can apply for the Tottenham job when Jol gets fired. You will probably have no chance at first but if you do a good job and build a reputation eventually you will have a chance. You can also get fired too.
The game is fun, but time-consuming usually you can play a lower division side all the way to the top over several seasons but this has become more difficult in recent versions. Or if you like you can play with one of the big boys and tackle Europe. You can also manage in other European Leagues or take over the National side when the manager gets fired.