This setting decides what your partner sees of each of your calendars. It never hides anything from you.
It's easy to hide or unhide your calendars from your partner in just a few seconds. Here's how:
Tap the menu icon (☰). Depending on your app version, it will appear either in the top-left corner of the Home screen or in the bottom-right corner of the tab bar
Select 'Sharing & Privacy'
Select 'Event Privacy'
Adjust the slider for each calendar to hide or unhide each calendar individually