You have opened a project and either opened or created a symbol in the symbol editor (Utilities > Master data > Symbol > ...). Edit > Property arrangements.
In this dialog, you create and delete property arrangements. These can then be selected and edited in the Property placement dialog, in the Property arrangement drop-down list.
Overview of the main dialog elements:
Popup menu:
The popup menu provides - depending on the field type (e.g. date, integer, multilingual) - the following menu items that are, depending on the situation, available for influencing the table or editing the values in the fields. You can find an overview of these popup menu items in the section Popup menu items.