How to echo this array?

Well your question is a bit unclear. $data['content'] is the array $data with an element 'content'. Is the array you have shown the element 'content' or the array $data itself?

In your controller something like:

PHP Code:

public function index()
{
    $data = array();

    $content = array(
        array(
            'subject_name' => 'Maths',
            'subject_author' => 'Peter',
        ),
        array(
            'subject_name' => 'English',
            'subject_author' => 'John',
        ),
    );
    $data['content'] = $content;

    $this->load->view('homepage', $data);
} 


In your 'homepage.php' view file something like:

PHP Code:

<?php if ( ! empty($content)) { ?>

     <?php foreach ($content as $item) { ?>

          <?php echo $item['subject_name']; ?>
          <?php echo $item['subject_author']; ?>

     <?php } ?>

<?php } ?>

I hope that helps but perhaps you were asking something more complicated that I have missed.

Best wishes

Paul.