Why this error appears stdClass::$pic_item?

I finally get the answer but still cannot explain my own answer if anyone can help me explain this codes out:

<?php foreach($pic as $pic_item): ?>
<img src="<?php echo base_url('assets1/images/slider/'.$pic_item->galleries_picture_name);?>">
<?php endforeach;?>

First, do I really need the foreach loop? Second, why $pic_item->galleries_picture_name works?

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