Breadcrumbs captures the trail of events leading up to an error or crash which helps to easily replicate the path a user took. By knowing the steps taken to throw the error, debugging can be reduced to minutes without the user needing to report it.
For context when debugging issues, developers often have to look at log files to see what the user was doing right before they experienced an error. Which is a very time consuming process.
With breadcrumbs the user has left a trail of clues for the developer. They hit the page, they clicked a button, then the error occured. Now we know exactly how to replicate this problem as a developer trying to reproduce it and fix it.
Activating this functionality is detailed in the specific language provider for each programming language and platform you are monitoring.