Can't understand the code in this section

Answer 1

The iframe shows some page inside your page such as youtube video.

Answer 2

Sorry i don't understand what is you question can you more specific?

Answer 3

...
<div class="section">
<h1><span>My Media</span></h1>
<iframe height="150" width="300" src="https://www.youtube.com/embed/Q6_5InVJZ88" allowfullscreen frameborder="0"></iframe>
</div>
... I can't understand this code .will u help me??