On running plays, there are blockers who clear the way for the ball carrier. Pick pressures work the same way for the defense.
One blitzer picks or blocks an offensive lineman, creating an alley for another blitzer to get through to the quarterback.
This example comes courtesy of Mike Macdonald when he was the Ravens Defensive Coordinator in 2023.
This was a 3rd-and-10. Baltimore aligned with 6 potential pass rushers near the line of scrimmage. Linebacker Roquan Smith stood over the center, creating a 5-man surface: