Service Exposure in Mendix: Publishing REST API, SOAP, OData & Others
Consuming Services in Mendix - REST API, SOAP | Mendix Evaluation Guide
Hi
You can refer the below learning path for rest api
https://academy.mendix.com/link/paths/133/Design-and-Publish-a-REST-API
As the Design and Publish learning path is more advanced, I would recommend following the Importing and Exporting learning path first, this also explains the basic integration concepts.