V$RECOVERY_FILE_DEST shows target OS or ASM directories, as specified in the db_recovery_area_dir initialization parameter, which are designated to contain flash recovery area files. If there is nothing visible in the table, confirm the setting of the initialization parameter. If both are null/empty, then there is no Flash Recovery Area defined for the database.
select * from v$recovery_file_dest;
NAME SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES CON_ID
----- ----------- ---------- ----------------- --------------- ----------
+RECO 1.3980E+10 8989442048 0 5 0
show parameter db_recovery
NAME TYPE VALUE
-------------------------- ----------- ------
db_recovery_file_dest string +RECO
db_recovery_file_dest_size big integer 13332M