This DMV is probably one of the most useful DMVs for developers and Business intelligence users since it describes the data type and other columnar information of the result set. Unlike sp_help which describes a table this particular DMV or DMF actually can be used to dynamically determine the datatypes and other usage options for any result set. i.e it could be very helpful when using .Net to create SSIS package or SSRS reports dynamically. It is important to remember that this DMV describes the result set and therefore the output may change based on the actual results and not the underlying table definition.
The basic usage is as mentioned sys.dm_exec_describe_first_result_set(Query here’,parameters,0 or 1)
Click here for the MSDN article on the above DMV