This simply acknowledges the starting base cost of your site. This is without any additions, extra pages, or custom elements which go above and beyond your chosen package.
Hosting is a necessary element for all websites. Once your site is complete, it needs to be "hosted" online so that people can access it. Webflow will be used for hosting your site and this fee will be paid to them. Depending on your website needs, this number might change slightly.
If you already have a site designed, you can choose "Development Only". Otherwise, you most likely need a site designed and built so choose the button for both.
Once you have finished step #3, choose how many pages you think you will need for this project.
I will reach out to clarify anything before finalizing your project.