The number of websites:
--> The number of websites means you can create n number of websites as per plan for example, Site1, Site2, Site3 etc...
Domain name hosted:
--> Unlimited domain hosted means you can point unlimited domain names to a single website.
For example, you have 2 domain names abc.com and abc12.net, you can point both the domain names to Site1.
similarly, if you have n number of domain names, you can point to a single website.