Right. Squarespace is a hosting provider and website builder that anyone should be able to use to build a website, typically a smaller scale website like a blog or a small to medium online store / e-commerce site. It's similar to Wix, Weebly, WordPress.com, and the website builders that some hosting providers offer.
Kubernetes is a tool large companies use to manage a large number of servers. Google invented it and open-sourced it so now it's free for anyone to use. It's not something people would use for a single website unless it was a huge website that required lots of servers, like FoxNews.com or something.