Complex sentence: A team that signs a Type A player gives its top draft pick to the club that the player is leaving; that club also receives a supplemental pick in the "sandwich" round between the first and second rounds.
Split into simpler sentences: A team that signs a Type A player gives its top draft pick to the club that the player is leaving. The "losing" club also receives a supplemental pick in the "sandwich" round between the first and second rounds.