how to plugin multilanguage?

Sorry for the bad English, I learn English

How to make the plugin multilanguage?

Spoiler: CODE INSERT

PHP:

<?php
/*
ExampleUI gemacht von SaveConnectionPE für alle!
*/
namespace Donate;
use pocketmine\Server;
use pocketmine\plugin\PluginBase;
use pocketmine\event\Listener;
use pocketmine\utils\TextFormat as TF;
use pocketmine\Player;
use pocketmine\command\{Command, CommandSender, CommandExecutor, ConsoleCommandSender};

class Main extends PluginBase implements Listener{
 
    public $prefix = "§9§lDonate §8§l»§r §7";
 
    public function onEnable(){
        $this->getServer()->getPluginManager()->registerEvents($this, $this);
        $this->getLogger()->info(TF::GREEN . "Plugin Activate.");
      
        @mkdir($this->getDataFolder());
        $this->saveDefaultConfig();
        $this->getResource("config.yml");
    }
  
    public function onDisable(){
        $this->getLogger()->info(TF::RED . "Plugin Deactivate.");
    }
  
    public function onCommand(CommandSender $sender, Command $cmd, string $label, array $args) : bool{
        switch($cmd->getName()){
            case "donate":
                if($sender->hasPermission("donate.use")){
                    $this->donateMain($sender);
                }else{
                    $sender->sendMessage($this->prefix . "§cУ вас нет прав§4!§r");
                    return true;
                }
                break;
        }
        return true;
    }
  
    public function donateMain($sender){
        $api = $this->getServer()->getPluginManager()->getPlugin("FormAPI");
        $form = $api->createSimpleForm(function (Player $sender, int $data = null){
            $result = $data;
            if($result === null){
                return true;
            }
            switch($result){
                case 0:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg1"));
                    break;
                case 1:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg2"));
                    break;
                case 2:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg3"));
                    break;
                case 3:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg4"));
                    break;
                case 4:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg5"));
                    break;
                case 5:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg6"));
                    break;
                case 6:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg7"));
                    break;
                case 7:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg8"));
                    break;
                case 8:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg9"));
                    break;
                case 9:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg10"));
                    break;
                case 10:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg11"));
                    break;
                case 11:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg12"));
                    break;
                case 12:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg13"));
                    break;
                case 13:
                    $sender->sendMessage($this->prefix . $this->getConfig()->get("donate.msg14"));
                    break;
            }
        });
        $form->setTitle($this->getConfig()->get("donate.title"));
        $form->setContent($this->getConfig()->get("donate.content"));
        $form->addButton($this->getConfig()->get("donate.button1"));
        $form->addButton($this->getConfig()->get("donate.button2"));
        $form->addButton($this->getConfig()->get("donate.button3"));
        $form->addButton($this->getConfig()->get("donate.button4"));
        $form->addButton($this->getConfig()->get("donate.button5"));
        $form->addButton($this->getConfig()->get("donate.button6"));
        $form->addButton($this->getConfig()->get("donate.button7"));
        $form->addButton($this->getConfig()->get("donate.button8"));
        $form->addButton($this->getConfig()->get("donate.button9"));
        $form->addButton($this->getConfig()->get("donate.button10"));
        $form->addButton($this->getConfig()->get("donate.button11"));
        $form->addButton($this->getConfig()->get("donate.button12"));
        $form->addButton($this->getConfig()->get("donate.button13"));
        $form->addButton($this->getConfig()->get("donate.button14"));
        $form->sendToPlayer($sender);
        return $form;
    }
}


 

PHP:

$player->getLocale();

for getting the language code of a player, if this is what you asking