A soccer team is made up of 11 different players. The position is basically just their position on the pitch. Every team has a goalkeeper then you have defenders, midfielders and strikers the number of which varies from team to team. The most common "formations" are 4-4-2 (4 defenders, 4 midfielders, 2 strikers) or 4-3-3 (4 defenders, 3 midfielders, 3 strikers)
Here is an example of the positions
goalkeeper
left back center back center back right back (defenders)
left midfield central midfield central midfield right midfield
striker
striker