555-1 waitfor delay '0:0:15' --

Looks like a T-SQL snippet. The key part is:

WAITFOR DELAY '0:0:15'

• This pauses the current SQL session for 0 hours, 0 minutes, and 15 seconds (i.e., 15 seconds).
• The trailing -- is a comment start; anything after -- on that line is ignored.
• The leading "555-1" is not valid SQL by itself—it's likely a label or step marker in an exam.

A clean example you could run is:

-- 555-1 WAITFOR DELAY '00:00:15'; PRINT 'Delay complete';

Notes:

• Using WAITFOR DELAY will hold any locks held by your transaction, so use with care in production.
• You can also delay until a specific time with WAITFOR TIME '23:59:00'.