When trying to print value from array getting error like Illegal string offset

I am rendering view in mail template but in my view i am getting following error when i use dd($row['product_name']); i get product name but not in following code don't know meaning of this error

@foreach ($order as $row)
        <tr>
            <td></td>
            <td></td>
            <td></td>

        </tr>
@endforeach

getting error like Illegal string offset 'product_name'

via Chebli Mohamed