cURL - to test web APIs with the POST method from a terminal

I am trying to build a connection between appian and Jenkins for testing purpose. So for that according to this document https://docs.appian.com/suite/help/20.4/Running_Automated_Tests_on_Expression_Rules_with_Jenkins.html 
I have created some sample test webAPIs, Now I want to test them. 
Document is saying "To test web APIs with the POST method from a terminal, try the following cURL command: curl - X POST -u [username]:[password] https://[Appian Site]/suite/webapi/[startTest API]"

I dont know what does terminal means here ? 
How could I test these APIs ?