NACH_VB is a standard SAP Structure so does not store data like a database table does. It can be used to define the fields of other actual tables or to process "Detailed output data (updating element)" Information within sap ABAP programs. This is done by declaring abap internal tables, work areas or database tables based on this Structure. These can then be used to store and process the required data appropriately. i.e. DATA: wa_NACH_VB TYPE NACH_VB.
The NACH_VB table consists of various fields, each holding specific information or linking keys about Detailed output data (updating element) data available in SAP. These include MANDT (Client), KNUMH (Number of output condition record), ERNAM (Name of Person who Created the Object), ERDAT (Date on Which Record Was Created)... See below for full list along with technical details, documentation, text table, check tables, foreign key relationships, conversion routines, relevant tcodes and example ABAP select code etc. .