FRMLS_LAYOUT_FIELDS 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 "RMS-FRM: Layout-Dependent Field Catalog" 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_FRMLS_LAYOUT_FIELDS TYPE FRMLS_LAYOUT_FIELDS.
The FRMLS_LAYOUT_FIELDS table consists of various fields, each holding specific information or linking keys about RMS-FRM: Layout-Dependent Field Catalog data available in SAP. These include SORT (Sequence of Table Columns), FIX (Table Column Is Fixed), COLWIDTH (Column Width)... 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. .