No kidding. Even if you are not a developer, you can still learn the basics of Salesforce REST API in just under 60 minutes. Here is a step-by-step do-it-yourself guide on how to make REST API calls and interact with Salesforce.
But first of all, what is Salesforce REST API? Here is a very simple explanation – Salesforce REST API allows you to interact with Salesforce from outside the Salesforce. That means that you can create/update/delete records in Salesforce from an external program. That means that you can issue a query to Salesforce and get the response. More