loginaction.php:

query($sql);
    $result = $result->fetch_assoc();

    if($result != null && password_verify($password, $result["password"])){
        unset($result["password"]);
        $_SESSION["user"] = $result;
        header("Location: user.php");
    }
}

and here is my registeraction.php:

query($sql);

if(mysqli_num_rows($check) > 0){
    echo "Jste již registrovaný na tento Email";
    exit();
}
$sql = "INSERT INTO user (name, surname, email, password) VALUES ('$name', '$surname', '$email', '$hashedPassword')";
$result = $conn->query($sql);

header("Location: login.php");

}

is this the good way to approach the login and register? Its not for a big app, just my testing. How could I improve my skills more and what is the best way possible if I want to start making proffesional websites