PHP login function

function login($email, $password){
global $conn;

if(isset($_POST['login'])){

    $email = stripslashes($_REQUEST['email']);
    $email = mysqli_real_escape_string($conn,$email);
    $password = stripslashes($_REQUEST['password']);
    $password = mysqli_real_escape_string($conn,$password);

    $user = $conn->query("SELECT * FROM `users` WHERE email = '$email' and wachtwoord = '$password'");
    $setonline = $conn->query("UPDATE `users` SET online = '1' WHERE email = '$email' and wachtwoord = '$password'");
    $rows = mysqli_num_rows($user);

    if($rows == 1){
        session_start();
        $_SESSION['id'] = $id;
        echo '<p class="text-green">Succesvol ingelogd! <i class="fas fa-spinner fa-pulse"></i></p>';
        header("refresh:5;url=dash.php");
        } else{
        echo '<p class="text-red">Verkeerd email en/of wachtwoord.</p>';
        }
    }
}