How does decode_entities() work?
The function decode_entities works as you expect.  It converts the HTML entity (&amp;#039;) into a single quote and returns the decoded string.

However, that single quote will be expanded into an entity again at some point downstream, when the page is rendered.  This is what inserts (provided you spell "description" correct) the following into your page's &lt;head&gt;:

&lt;meta name="description" content="We&amp;#039;re in this together" /&gt;


I would not worry about this.  The above is a perfectly valid HTML meta-tag and will be interpreted correctly for SEO purposes, etc.