Some help needed

I was advised to try to promote my business with SMS bulk. I am in search of new ways of promotion. In the process of registration via the service, it asks me for my API and I see the following message: "The BSG API uses HTTP verbs and a RESTfull endpoint structure. An access key is used as the API Authorization framework. Request and response payloads are formatted as JSON, using UTF-8 encoding and URL encoded values". This is too much for me))). I do not have a person who could help me and there so so many unfamiliar words to me)). So, guys, your help is needed, maybe someone could explain, here is the service I mean : Thanks for any help.