Salesforce module provides you with the ability to select one from two "Message Queue" options.
Standard Message Queue
The Standard Message Queue is based on Cron jobs. By default, the cron job generates schedules every 1 minute.
For Cron installation refer to “Magento 2 CRON Setup“ article
How to enable Salesforce Standard Message Queue in Magento:
Go to Magento Admin panel
Click Salesforce (on left sidebar) - General Configuration - Advanced (tab)
Set "Message Queue" option to "Standard" and Save Config
Additionally, cron run settings can be modified
Go to Magento Admin panel
Click on Stores - Configuration - Advanced - System - Cron configuration options for group:tnw_salesforce_crons tab
RabbitMQ message queue
RabbitMQ message queue is an open-source message broker that offers a reliable, highly available, scalable, and portable messaging system. Message queues provide an asynchronous communications mechanism. It supplies faster data synchronization.
For RabbitMQ installation refer to “RabbitMQ Overview“ Magento devdocs article
How to enable Salesforce RabbitMQ Message Queue in Magento:
Go to Magento Admin panel
Click Salesforce (on left side bar) - General Configuration - Advanced (tab)
Set "Message Queue" option to "RabbitMQ"
Click Save Config