Estás llamando al método Open de un recordset, este método recibe como argumentos
SQL = Query
oConn = Conexión activa a tu base de datos
Los dos últimos números son el tipo de cursor y el tipo de cerrojo respectivamente
Cita: In ADO there are 4 different cursor types defined:
* Dynamic cursor - Allows you to see additions, changes, and deletions by other users.
* Keyset cursor - Like a dynamic cursor, except that you cannot see additions by other users, and it prevents access to records that other users have deleted. Data changes by other users will still be visible.
* Static cursor - Provides a static copy of a recordset for you to use to find data or generate reports. Additions, changes, or deletions by other users will not be visible. This is the only type of cursor allowed when you open a client-side Recordset object.
* Forward-only cursor - Allows you to only scroll forward through the Recordset. Additions, changes, or deletions by other users will not be visible.
The cursor type can be set by the CursorType property or by the CursorType parameter in the Open method.
Fuente:
http://www.w3schools.com/ado/ado_ref_recordset.asp
Salud