It allows you to view when a change was made to the step, see what the previous/old changes were and to revert the new change to a previous/ old change. This is a very helpful feature, especially when using the Calculator step.
In this example, the calculator step is used and it is populated with code as illustrated in the below image. To view the change log in the step, click on Change Log as highlighted.
The below page will appear. To view the different changes that were made in the step, click on one of the change (update) logs on the left and the change will appear on the right.
To revert a previous or old change, select the required change by clicking on the change log and click Revert as highlighted in the below image.
The below page will appear with the old change in the Properties tab. Click the Save Step button to save this change.