The discharge papers state
"Northern France GO 33 WD 45
(which I think I understand),
Central Europe AG 2006
Rhineland AG 2006.
What do these references mean?
It is difficult to be certain without seeing a picture of that part of the discharge papers, but I suspect that it should actually read:
Central Europe AG 200.6
Rhineland AG 200.6
where the 200.6 are the Adjutant General's Office decimal file system reference for Badges, citations, decorations, and awards.
This should therefore refer to the Rhineland campaign (15 September 1944 – 21 March 1945) and the Central European campaign (22 March – 11 May 1945).
However, the date that the papers were issued is critical as the Rhineland campaign doesn't appear to be listed as a separate entry in the 1951 supplement linked above.
"Northern France GO 33 WD 45"
is more straightforward. "GO 33 WD 45" stands for War Department General Order 33, dated 1945. The General Orders of the War Department for 1945 are available online in PDF format.
General Order 33 WD 45 specified the geographical combat zone, and time limitation for the following Bronze Service Star Campaigns related to the European African Middle Eastern Campaign (EAME) medal:
GO 33 WD 45 was subsequently amended by GO 40 WD 45. This is of particular importance in your case as GO 40 WD 45 added the Rhineland campaign (changing the name of the campaign from 'Germany' to 'Rhineland'.