I am newby to DB2 Stored Procedure and wish someone could explain to me what :WS-FUND-INS-ID:WS-FUND-INS-ID-NI and :WS-FREQ-CD:WS-FREQ-CD-NI are about?

EXEC SQL
SELECT INS_ID
,DISTN_FREQ_CD
INTO :WS-FUND-INS-ID:WS-FUND-INS-ID-NI...