English A profit from Polish middles is achieved as with simple middles, if the actual outcome hits both (sometimes more) different outcomes.
Example of a simple middle: there are two bets: total over 0.5, odds 2.05, and total under 1.5, odds 2.50.
If exactly one goal is scored in this game, the result will fall under both events, giving the player twice the win. That means hitting the middle.
In the case of a Polish middle, the calculation scheme is somewhat more complicated (it is described in detail on the Polish middles page).