The ELO is a points system which is given to each team in relation their standard of play: wins, draws and losses. Based on that you can estimate the win probability or even the number of goals they will score in a match.
The better a team is, the greater their ELO value is. If a team with a lower ELO beats one with a higher ELO, they get more points than if it were the other way around.
The ELO points system determines a general ranking in which the teams are ranked on a global scale and also ranked based on the competition the team play.
