Buffer Publish is integrated with Zapier, IFTTT, and Integromat. These are all web automation tools, described as the "glue" that connects hundreds of other web apps. In these tools you're able to create workflows (known as Zaps in Zapier, Applets in IFTTT, and Scenarios in Integromat). These workflows start with a trigger, which is an event in an app which kicks off the workflow, and end with an action, which is an event that's completed automatically in a second app.
The types of automations you could set up using these tools include things like sending tagged articles from Feedly to your queue, sending new WordPress posts to your queue, copying posts from your queue to a Google Sheet, and sending posts from your queue to Slack.