oop.php

<?php declare(strict_types=1);

class Player {

   private $name;

   function __construct(string $name) {

      $this->name = $name;

   }

   function getName(): string {

      return $this->name;

   }

}

class Team {

  private $players = [];

  function addPlayer(Player $player) {
    $this->players[] = $player;
  }

  function printPlayerNames() {

    foreach($this->players as $player) {
      echo $player->getName(), "\n";
    }
  }
}

$team = new Team('red');
$player = new Player('john');

$team->addPlayer($player);
$team->printPlayerNames();