It works by a sender, who is an agent from the supposed lottery organization, tells the victim that they should deposit the check, often for $25,000, into their bank account. Afterward, they are instructed to wire to the sender an amount, commonly for $5,000 or $10,000, as a fee before they can receive their winnings.
Sometime later, the "winner" discovers that the $25,000 check has bounced and they are out the $5,000 they sent.
But the losses could be even higher if they have to cover the fraudulent check or disclosed to the scammers data on their bank account.