My one-page HTML site was hacked

> When I use google to search for this website, under the link for the home page - there's a text that's not actually on the web page (looks like ads)

Most likely stale cache from previous owner of your domain, of which there has been plenty[1] or was parked in-between.

Setup google webmaster tools for your domain.

>It's a one-page site in Html, how can static Html be hacked by hackers?

Plenty of ways, the source in your computer to the server which hosts your website. Using static website just limits the attack surface from the website itself.

[1]https://web.archive.org/web/*/https://hostrider.com/

When did you buy the domain and update the website?

If there was a website there before, it could just be that Google hasn't updated their search index.

Adding your site to Google Search Console can help, so you can request for the page to be reindexed.

Your server can be compromised. If you are lazy just drop it in a CDN like netlify

Check which JavaScript is loaded. There can be malicious js in a static site

Verify with Google Search Console

Hi, I forget what the exact cause was, but awhile back, I noticed that for The Guardian in Bing, the description blurb started out with "The Guardian, a far left wingnut rag..." - I told them about it and they had this recurring problem fixed. It was some sort of cache poisoning somewhere that is out of your control. So if you are sure you have not been hacked...

Google Webmaster Tools might have some help pages - do you have an account for managing your domain? IIRC, there might be a field somewhere where you can set this description. I know you can manually set this in some fashion... You have to prove you own the domain etc first. And check or get a Bing Webmaster type account as well.