Help me out (Im new to developing PM plugins - erros in my code)

PHP:

<?php

namespace Hello;

use pocketmine\plugin\PluginBase;
use pocketmine\command\Command;
use pocketmine\command\CommandSender;

class Hello extends PluginBase{

    public function onEnable(){
        $this->getLogger()->info("onEnable() has been called!");
    }
 
    public function onLoad(){
     
    }

    public function onDisable(){
        $this->getLogger()->info("onDisable() has been called!");
    }
}



public function onCommand(CommandSender $sender, Command $command, $label, array $args){
    if(strtolower($command->getName()) === "hello"){
        sender->sendMeassage("hello there".sender->getName()"!");
        return true;
    }

    return false;

I apologize for my terrible mistakes, im learning through my mistakes

You should get a basic code editor to delete syntax errors.
However try this:

PHP:

<?php

namespace Hello;

use pocketmine\plugin\PluginBase;
use pocketmine\command\Command;
use pocketmine\command\CommandSender;

class Hello extends PluginBase{

public function onEnable(){
  $this->getLogger()->info("onEnable() has been called!");
}

public function onLoad(){

}

public function onDisable(){
  $this->getLogger()->info("onDisable() has been called!");
}


public function onCommand(CommandSender $sender, Command $command, $label, array $args){
  if(strtolower($command->getName()) === "hello"){
   $sender->sendMeassage("hello there".$sender->getName()."!");
   return true;
  }
 }
}

So

Thanks for the reply i cant test it now :/ anyway what was my mistake, what was the syntax error?

Curly brackets were wrong and you forgot a "$" before "sender".
Other things are fine I think

And close braces