What is the meaning of this anomaly warning message?
Based on the sample table in your link, I'd suggest it's taking issue with fields such as:

phone1
phone2


or

notes1
notes2
notes3


This may indicate a design flaw (but not always), and if so, one that can probably be corrected by more descriptive field names or perhaps a child table.

For example, someone might have more than one phone number... what if someone has three? Seven? Maybe data like this should be in a subtable, and perhaps even with some sort of indicator of what type of phone number it is, whether it's a preferred phone number, etc. Alternatively, maybe just renaming the fields to phone_home and phone_cell will be enough to eliminate confusion and allow you to collect all of the data you need.