Elo is actually the surname of the guy who invented the system. Lots of people mistakenly refer to it in acronym form as ELO, which is…not wrong…if you’re yelling his name
In this case, support’s answer wasn’t “wrong” in the literal sense, but they could have done a bit of a better job explaining it. For example: Elo assigns a rating to each participant in a matchup, and calculates a win-loss projection based on the difference in their ratings. After the match resolves, a point rating based on how fair or unfair the match was is taken from the loser goes to the victor, thereby adjusting each player’s elo up or down, but maintaining roughly the same total amount of elo in the population.
If you want to know more, there’s always the wiki