What do green, yellow and red cards mean in high school field hockey?

Under NFHS rules, cards suspend the player and the team plays one player short while the card is served:

• Re-entering early: a suspended player who stays in or re-enters before serving the full time is removed to serve the remaining time. A disqualified player who stays in or re-enters is removed, and the team plays short (Rule 8-2-1, since 2023).
• Suspended goalkeeper: the coach removes one field player, and the goalkeeper is replaced by another fully equipped goalkeeper. If the goalkeeper was suspended only for a jersey violation, the goalkeeper may stay in and a field player is removed instead (Rule 8-2-1, 2025).
• Coaches can also be carded. If a team asks for a second time-out and play is stopped, the coach gets a yellow card and the team removes a field player for 5 minutes of playing time.