Can't Display Image in wordpress - php

Question

I try to add images in a columns using Advanced Custom Fields but the images doesn't display. But it displays the url of the images.
<div class="container">
<?php if( have_rows('columns-1-services') ): ?>
<div class="row">
<?php while(have_rows('columns-1-services')):the_row(); {
$image_1 = get_sub_field("images-1");
$image_2 = get_sub_field("images-2");
$image_3 = get_sub_field("images-3");
$image_4 = get_sub_field("images-4");
} ?>
<div class="col-md-3 services"><?php echo "$image_1"; ?></div>
<div class="col-md-3 services"><?php echo "$image_2"; ?></div>
<div class="col-md-3 services"><?php echo "$image_3"; ?></div>
<div class="col-md-3 services"><?php echo "$image_4"; ?></div>
<?php endwhile; ?>
</div>
<?php
else :
// no rows found
endif;?>
</div>

Answer 1

As LucasNesk has said, the get_sub_field("image") function is returning a url rather than a full img tag.
Rather than using the url in a tag, I would recommend changing the field in settings to return the ID, and then using WordPress functions to output the image tag. That way you can easily use a thumbnail size and WP handles a responsive srcset for you.
From https://www.advancedcustomfields.com/resources/image/#template-usage
<?php
$image = get_field('image');
$size = 'full'; // (thumbnail, medium, large, full or custom size)
if( $image ) {
echo wp_get_attachment_image( $image, $size );
}
?>

Answer 2

It happens because you are rendering the image URL directly into the HTML page.
Try to put it in a Image tag at the src attribute, like:
<div class="col-md-3 services">
<img src="<?php echo $image_1; ?>">
</div>
This will render your URL in the source attribute and load your image properly.
References of img tag: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img