Webflow accounts are completely free if you have no more than 2 websites. But, to launch any website online you build you'll need to pay for hosting. If you've never built a website before, you can think of it like rent for your online home.
When you use some platforms (like WordPress), you bring your own hosting with you and manage your own backups. Other platforms (including Webflow, Squarespace and Shopify) manage your hosting and backups for you.
Webflow's CMS hosting is $16 USD per month (billed annually), which is a good fit for most of our projects. You can visit the Webflow website to read more about their pricing, plans and inclusions to choose the hosting that's right for you.