Check filename ending & a fileuploader

<?php
$filetype = wp_check_filetype('image.jpg');
echo $filetype['ext']; // will output jpg
?>

To use with ACF

if ( have_rows( 'file_uploader' ) ):

		echo '<section class="section col-1 no-full-width inner-grid" style="flex-direction: column;">';
		echo '<p style="padding-bottom: 20px;"><strong>Vedlagte filer<span class="dashicons dashicons-download"></span></strong></p>';
		echo '<div class="download-file-container">';

		while ( have_rows( 'file_uploader' ) ) : the_row();

			$file = get_sub_field( 'upload_file' );

			if ( $file ):

				$filetype = wp_check_filetype( $file['filename'] );

				$icon = $file['icon'];
				if ( $file['type'] == 'image' ) {
					$icon = $file['sizes']['thumbnail'];
				}
				?>

				<div class="rc-Employee_Contact" style="align-self: flex-start; padding-bottom: 40px;">
					<div class="img-container">
						<img src="<?php echo $icon; ?>" alt="icon">
					</div>
					<a href="<?php echo $file['url']; ?>"><span>Last ned <?php echo $filetype['ext']; ?></span></a>
				</div>

			<?php endif;

		endwhile;

	else :

		// no rows found

		echo '</div>';
		echo '</section>';

	endif; ?>