The Show Row Count control allows you to set a 'row count' for a repeatable section of data.
Where Show Row Count is set to true, the Title of a section will append a "Count" for the number of records added to the section. This means when the section is collapsed, you are able to tell how many records have been added to the section:
And when you expand the section, you are then able to see the records/add more:
How to configure the Show Row Count in Platform
To add a Show Row Count to a repeatable section, you need to make sure you are in Draft mode in Platform, find the section you want to add the Show Row Count to, and scroll across to the Show Row Count Control:
When set to Yes, the Show Row Count will be enabled in your journey interface for that Section.