HI Ajay,

In Pega we have two concepts i.e. Connector and Service.

If you want to connect to any webservices like REST/SOAP/etc from the Pega application to process your requests then you can create the corresponding Connect- rules.

Similarly if Pega wants to provide Service to external systems then you can create the corresponding Service- rules. 

I am sharing the sample reference document for creation of the Service-REST in attachment. Hope this information might be helpful to you.

Regards

Mahesh