Die durch Umgliederung der IV./JG 54 in eine Me 262 - Jagdgruppe (II./JG 7) freiwerdende 4. Staffel ist geschlossen Gen.Lt. Galland zur Aufstellung einer unter seiner Führung stehenden und dem JG 7 anzugleidernen Jagdstaffel Me 262 zur Verfügung zu stellen.
"The 4. [Staffel] — freed up by the conversion of IV. [Gruppe]/JG 54 into an Me 262 Jagdgruppe (II./JG 7) — is placed, as a complete unit, at the disposal of Gen.Lt. Galland for the establishment of an Me 262 Jagdstaffel under his leadership and attached to JG 7."
I think there's an ambiguity in that "4. Staffel" doesn't mean 4./JG 54 (part of the I. Gruppe) here but rather "the fourth Staffel of the IV. Gruppe" (i.e. 16./JG 54).
The reason for that is that JG 54's Gruppen had four Staffeln each while JG 7 was set up with only three per Gruppe
but with gaps in the numbering to allow for a fourth. So the JG 7 structure was:
I. Gruppe: 1., 2. and 3./JG 7
II. Gruppe: 5., 6. and 7./JG 7
III. Gruppe: 9., 10. and 11./JG 7
So Galland was to get the Staffel that was surplus in the reorganisation. As to "geschlossen" in this context, it can mean "united" or "in a body" and I take that to mean here that Galland will get all the Staffel's elements: flying, technical, signals, admin. etc. You'll often see in other reorganisations that the pieces were split up and assigned to various units.