The Oracle database doesn’t allow you to execute a SELECT statement without a FROM clause. You can't, for example, do SELECT 2 + 2, you must do SELECT 2 + 2 FROM dual. “dual” is a fictional table which exists solely to allow these sorts of operations.

What it isn’t meant for is Aspirist’s sample, from the Sidebar.

CREATE OR REPLACE VIEW ITIL_SERVICE_V1 AS
SELECT 'SS1' SERVICIO, 'Low' IMPACTO TIME, 'Low' URGENCIA TIME, 48 RESPONSE TIME, 96 RESOLUTION TIME, 4 ESCALATES TIME FROM DUAL -- Priority Low
UNION ALL
SELECT 'SS1', 'Low', 'Medium', 48,96,4 FROM DUAL -- Priority low
UNION ALL
SELECT 'SS1', 'Medium', 'Low', 48,96,4 FROM DUAL -- Priority low
UNION ALL
SELECT 'SS1', 'High', 'Low', 1.5,24,1 FROM DUAL -- Priority Medium
UNION ALL
SELECT 'SS1', 'Medium', 'Medium', 3,36,2 FROM DUAL -- Priority normal
UNION ALL
SELECT 'SS1', 'Low', 'High', 48,96,4 FROM DUAL -- Priority low
/* SNIP a few dozen lines for brevity */
SELECT 'HS2', 'Low', 'High', 48,96,4 FROM DUAL -- Priority low
UNION ALL
SELECT 'HS2', 'Medium', 'High', 1.5,24,1 FROM DUAL -- Priority medium
UNION ALL
SELECT 'HS2', 'High', 'Medium', 0.30,16,0.30 FROM DUAL -- Priority High
UNION ALL
SELECT 'HS2', 'High', 'High', 0.15,8,0.15 FROM DUAL -- Priority Urgent
UNION ALL
--Asset Managemetn; (AM3)
SELECT 'AM3', 'Low', 'Low', 48,96,4 FROM DUAL -- Priority Low
UNION ALL
SELECT 'AM3', 'Low', 'Medium', 48,96,4 FROM DUAL -- Priority Low 
/* SNIP 800 more lines of the same */
UNION ALL
SELECT 'ACC45', 'Medium', 'High', 1.5,24,1 FROM DUAL -- Priority medium
UNION ALL
SELECT 'ACC45', 'High', 'Medium', 0.30,16,0.30 FROM DUAL -- Priority High
UNION ALL
SELECT 'ACC45', 'High', 'High', 0.15,8,0.15 FROM DUAL -- Priority Urgent;

If you’re asking yourself, “Did someone just hard code values into a view so that it behaves sort of like a table that you can’t ever change easily?”, the answer is, “Yes.”

If you’re asking yourself, “Why?”, there is no answer. Some things were not meant to be understood by mere mortals.