The asterisk (*) indicates that the record count has not been accurately determined. This occurs when a table is opened in an enterprise geodatabase or database that has more than 2000 records. For performance reasons, the table window only accesses the first 2000 records. Use the 'Move to End of Table' button in the table window to determine the total number of records.
This process may take a long time to complete if the layer has a large number of records.