To learn about the benefits of a VPN, read Benefits of a VPN.
Hotspot Shield Basic provides US IP addresses, which allow users to access blocked content in the US only. The content that's accessible with the free version is limited; you will not be able to stream most types of video content. There are data limits and speed limits on Basic.
If you want to have full access to US sites and non-US IP addresses, you will need to upgrade to Premium.
The benefits of Premium are outlined here.
You can try a Premium account for free here.