Svelte-kit is a framework for building website with Svelte. It is a front end javascript library with the following features -

• Server and client side rendering
• comes with routing systems
• provides a backend API
• code splitting

This is also a popular SPA framework. According to mdn web docs

An SPA (Single-page application) is a web app implementation that loads only a single web document, and then updates the body content of that single document via JavaScript APIs such as XMLHttpRequest and Fetch when different content is to be shown.

The easiest way to start building a SvelteKit app is to run

npm init svelte my-app

In order to have a proper functioning svelte app you need to make sure you have an updated version of node js installed to your system. Svelte sometimes runs into problems with older versions of node.

If you use vs code extensions svelte for vs code is a good extension to install. This will provide us with syntax highlighting for svelte components.

Learn more about svelte kit here