$my_arr1 = array();

$my_arr1 = array("name" => "Evgen", "age" => 40, "weight" => "65 kg");

$my_arr1["name"] = "Evgen";
$my_arr1["age"] = 40;
$my_arr1["weight"] = "65 kg";

$myCount = count($my_arr1);
// $myCount = 3

foreach($my_arr1 as $key => $value)
{
     // на первой итерации
     // $key = "name"
     // $value = "Evgen"

     // на второй итерации
     // $key = "age"
     // $value = "40"

     // на третьей итерации
     // $key = "weight"
     // $value = "65 kg"
}