I cannot insert data to database using localhost xampp through PHP

Fatal error: Uncaught mysqli_sql_exception: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '@gmail.com,123,123)' at line 1 in C:\xampp\htdocs\practice\db_connection.php:43 Stack trace: #0 C:\xampp\htdocs\practice\db_connection.php(43): mysqli_query(Object(mysqli), 'INSERT INTO sig...') #1 {main} thrown in C:\xampp\htdocs\practice\db_connection.php on line 43

$sql = "INSERT INTO signup (FirstName,Lastname,UserName, Email, Password, ConfirmPassword) VALUES ($Fname,$Lname,$Uname,$email,$password,$password2)";