echo returns "Array"

Thanks, but I bumped into another problem. The previous piece of code was written in a page template together with an HTML form. I didn’t know which URL to put into the action attribute, so I made a new PHP file called database_list.php (in the child theme folder):

<?php
	if (isset ($_GET['upis'])&&!empty($_GET['upis'])){
	$upis=$_GET['upis'];
  	$mocnesi=$wpdb->get_var("SELECT engleski, prijevod FROM rjecnik WHERE id = $upis");
	echo $mocnesi;
  	}
?>

And I moved the form code into the main page:

<form action="database_list.php" method="get">
  Upisite rijec!
  Trazena rijec: <input type="number" name="upis">
  <input type="submit" value="Trazi">
</form>

I don’t know how to return the $mocnesi value found by the query to html to display. Any help?

I had problems with picking the right array type. Works with associative. Thanks!