You can have as many WordPress.com websites as you like under your WordPress.com account, be they Free or Paid websites. You will need to pay for each Paid website individually.

If you’re not using the WordPress.com version of WordPress, you’ll be using the WordPress.org version, which can be turned into a Multisite website.

A WordPress Multisite can have many websites running off the single WordPress installation.

Each Multisite website can have its own domain.

However, for this to happen, your cPanel hosting account needs to allow add-on domains or aliases.

For each additional website’s domain you have in WordPress Multisite, you’ll need to add that domain as an add-on domain or alias in cPanel

How much is WordPress hosting?