What is a hosting account?
A hosting account can be seen as the land you build your house (website) on. Your domain name is the address, and the website the house.
Hosting accounts come in many different shapes and configurations and you need to talk through your preferences/future plans with your web developer/designer so that they can best provide the correct sized account for your needs.
It's not only the size of your actual website to take into consideration. For example if you plan to store your emails on your hosting account to sync them on several devices you'll need a bigger block of land to keep that information stored and accessible at all times. The same goes if you want to keep/swap files like meeting minutes, photos or pdf (or other) files. But if you'd like to have a simple website with emails you maintain regularly, you'll only need a small block of land.