How to print an entity bundle field from one with multiple values
Try the following and load the actual entity to get its field values.

The code assumes you have drupals entityTypeManager injected via dependency injection. Otherwise use \Drupal::entityTypeManager() isntead of $this-&gt;entityTypeManager()

// Get the entity ids.
$entityIds = $this-&gt;entityTypeManager()-&gt;getStorage('school_objects')-&gt;getQuery()
  -&gt;condition('type', 'homepage')
  // Add more conditions if you need.
  -&gt;execute();
// I assume only one id is returned and reset the array. Otherwise go over 
// each Id with a foreach() and do this in a loop.
$entityId = reset($entityIds);
$schoolObject = $this-&gt;entityTypeManager()-&gt;getStorage('school_objects')-&gt;load($entityId);
// Now get the values of your field. I assume the fields machine_name is 'field_hero_banners'. Adjust if needed.
$values = $schoolObject-&gt;get('field_hero_banners')-&gt;getValue()
// Loop over all values.
foreach ($values as $item) {
  $value = $item['value'];
}