Edited.
Regarding this article: Why is the field set to blank instead of null and vice versa in ArcGIS Pro?
A field can have a null value when the data type is set to numeric or the Allow NULL check box is enabled. It is not possible to have a blank value as an integer such as the number zero ('0') is also a value. For example, in an attribute table, when the value in the No. of Siblings field is deleted, the field is set to <Null> instead of blank, demonstrating the value does not exist.
I'm finding the wording in that article to be awkward and misleading. For example, should the blue "or" actually be an "and"?
I've submitted feedback via the feedback button. But I often don't hear back about feedback.