Action Menu Item Conditions

I'm attempting to add an menu item to an Action Menu for a backend page for a Dynamic Module. However, I'm having some difficulty finding any sort of documentation on what the various fields do.

Specifically, I'm attempting to add a ContentItemWidgetElement. I want it to be visible based on the user's permissions. It appears that the "Condition" field is what would control this, as it's help text states "An expression to determine whether the item should be visible". However, I can't figure out what kind of expression or what the format should be of that expression is needed.

Is there any kind of help doucments that can be used to cover these options?