Untitled

<?php
// Botão enviar
if(isset($_POST['btn-entrar'])):
    echo "Clicou";
endif;
?>

<html>
<head>
    <meta charset="utf-8">
    <title>Login</title>
</head>
<body>

<h1> Login </h1>

<form action="<?php echo $_SERVER['PHP_SELF']" method="POST">
Login: <input type="text" name="login"><br>
Senha: <input type="password" name="senha"><br>
<button type="submit" name="btn-entrar"> Entrar </button>
</form>

</body>
</html>