
In Auto Racing, the Checkered (Chequered) Flag signals that the race or session is over and the winner has been crowned. In NASCAR it usually means race finished/winner but in FIA-sanctioned championships and IndyCar it means session finished/winner however it means pretty much the same thing. iRacing also uses this flag to signal that the session/race is over and the winner has been crowned.
NASCAR: Race Finished/Winner.
IndyCar & FIA-sanctioned championships: Session Finished/Winner.
iRacing: Session/Race has finished and winner declared.