Problem connection form to the mysql php database [closed]

I try to access the database from a form, and it does not take me anywhere. If someone could help me ... thank you!

The code is as follows:

<?php
session_start();

    if(isset($_SESSION['admin'])){
        require '../php/Funciones.php';
        $obj = new Funciones();

        if(isset($POST['titulo'], $POST['contenido'])){
            $subir = $obj->subirPublicacion($_POST['titulo'], $_POST['contenido'], $_SESSION['admin']);

            if($subir == true){
                echo '<span class="alert alert-success ">Artículo dado de alta</span>';
            }
        }

?>

...                 

Admin Panel

        <form action="http://localhost:8888/cmsbasico/admin/publicacion.php" method="post">
            <input type="text" placeholder="Usuario" name="user" class="form-control"/>
            <br>
            <input type="password" placeholder="Password" name="pass" class="form-control"/>
            <input type="submit" class="btn btn-info pull-left" style="margin-top: 20px;" value="Iniciar sesión"/>
        </form>

    </div>

The function I'm using is:

public function logIn($user, $pass){
            global $pdo;

            $query = $pdo->prepare("
                  SELECT *
                  FROM admins
                  WHERE usuario = :user AND pass = :pass
            ");
            $query->execute([
                'user' => $user,
                'pass' => $pass
            ]);

            return $query->fetch();

        }