Lets say you are pushing leads from AEM to salesforce.
so for dev and other lower environments, the url to post lead to salesforce will be like:
https://sandbox.saleforce.com/abc/xyz
but for prod it will be
https://your_company.salesforce.com/abc/xyz
you will create configs for the above urls
The corresponding config will be used by the specific instance (dev author or pub prod) based on its runmode.
Refer to below article
Run Modes