FMGLFLEX01_DATA 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 "General Ledger: Technical Fields in Data Part of Line Items" 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_FMGLFLEX01_DATA TYPE FMGLFLEX01_DATA.
The FMGLFLEX01_DATA table consists of various fields, each holding specific information or linking keys about General Ledger: Technical Fields in Data Part of Line Items data available in SAP. These include RVERS (Version), LOGSYS (Logical system)... 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. .