Meaning

hey, can anybody help me to understad that code:
SELECT companies.Contact_Company AS am_label1,
ISNULL(Incident_CNT,0) AS NumberOfIncidents
FROM (
SELECT DISTINCT Contact_Company FROM HPD_Help_Desk
) companies LEFT OUTER JOIN (
SELECT COUNT(*) AS Incident_CNT, Contact_Company AS am_label1
FROM HPD_Help_Desk
WHERE Status< 5
AND DATEADD ("s", submit_date, '1/1/1970') >= CAST(CONVERT(char(8),GETDATE(),112) AS datetime)
GROUP BY Contact_Company
) IncidentsByCompany
ON companies.Contact_Company = IncidentsByCompany.Contact_Company

Thank you.