Google often frustratingly creates a snippet, or the summary shown below the big blue links in search results, from your page’s text instead of the meta description you wrote.
(This has been going on far longer than the somewhat recent & more noticeable change to generating titles.)
This depends on the query. For example, if a searcher uses keywords not mentioned in your meta description, Google is unlikely to display it.
Unfortunately, sometimes this means a crappy result like displaying copy from your footer. This looks uncompelling and is often formatted poorly, so it won’t boost CTR!
However, you aren’t powerless here…
The ‘data-nosnippet’ attribute lets you designate sections of your site that Google won’t use. This helps the snippet look more presentable in the worst case scenario.
At scale across many pages, little optimizations like this make a big difference in your organic search results, boosting CTR which in turn improves keyword rankings, so more organic traffic & conversions!