Ah SEO... One of those easy things you can just take care of with a free plugin and never worry about again.
After all, if you just design your own free website and put your keywords 35 times on the page, Google will rank you high right?
Here's a fun graph of one small piece of thousands of pieces that all link together to impact your SEO in ways you can't even imagine.
See that ugly cluster on the bottom left? That's a group of spam links that this website owner or their marketing person decided was a good idea to purchase or build at one point in time. It could have been a previous owner too, or even a competitor trying to harm their rankings.
And the branches? Those are tiered links. The goal is to cut off the old spam links at Tier 1 which disconnects the site from Tier 2, 3, and 4.
Then we'll work on building new quality backlinks, citations, content, and other on-page and off-page signals to help them recover.
It's easy, though. Just design your own website and install a plugin.