ds-section is used to wrap blocks and provide background color
<div class="ds-block">
<h2>This is a block NOT wrapped in a scection</h2>
</div>
<div class="ds-section ds-section--bg-grey">
<div class="ds-block">
<h2>This is a block wrapped in a scection</h2>
<p>Sections can wrap multiple blocks</p>
</div>
</div>
<div class="ds-block">
<h2>This is a block NOT wrapped in a scection</h2>
</div>