Untitled

<html>
<div class="form-group">
            <label for="exampleInputUsername">Username</label>
            <input type="text" name="name" class="form-control" id="exampleInputUsername" placeholder="enter username">
            <span class="error_message"><?php echo $nameErr;?></span>
          </div>

          <div class="form-group">
              <label for="exampleInputEmail1">Email address</label>
              <input type="email" name="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email">
              <span class="error_message"><?php echo $emailErr;?></span>
              <small id="emailHelp" class="form-text text-muted">We'll never share your email with anyone else.</small>
            </div>
</html>

<?php
if (isset($_POST['signupBtn'])) { // missing open brace
    $name = trim($_POST['name']);
    $email = trim($_POST['email']);

    $hashed_password = password_hash($pwd, PASSWORD_DEFAULT);
    $encrypted = password_hash($cpwd, PASSWORD_BCRYPT);

    // check if user already exist
    $username_exist = "SELECT * FROM signup WHERE username='$username'"; // what is $username?
    $email_exist = "SELECT * FROM signup WHERE email='$email'";

    $username_result = $dbh->prepare($username_exist);
    $email_result = $dbh->prepare($email_exist);

    $username_result->execute();
    $email_result->execute();

    if ($username_result->rowCount() > 0) { // you are assuming your $username_result execute successfully without checking
                // since $username_result execute without binding params, it fails
        $nameErr = "username already taken";
    } elseif ($email_result->rowCount() > 0) {
                // same here, you execute statement without binding params and you didn't check if $email_result returns true/false
        $emailErr = "email taken";
    } else {
        // insert into database
        $insert="INSERT INTO signup(username, email,password,confirm_password) VALUES(:name, :email, :pwd, :cpwd)";
        $statement = $dbh->prepare($insert);
        $statement->bindParam(':name', $name);
        $statement->bindParam(':email', $email);
        $statement->bindParam(':pwd', $hashed_password);
        $statement->bindParam(':cpwd', $encrypted);

        $statement->execute();

        if ($statement->rowCount() > 0) {
            $result = "row inserted";
        }else {
            $result = "insertion failed";
        }


    }
} // missing closing brace
?>