who are they peacekeeping from?
It establishes a buffer zone between Israel and Egypt with restrictions on the number and types of troops and weapons. It is monitored by the UN but there are always 3 BN of Infantry and support troops in the zone, manning OPs, mounting patrols, gathering Intel.
Pretty good info here: https://en.wikipedia.org/wiki/Multinational_Force_and_Observers
I was in the 9th iteration Dec 85 - May 86 with the 9th ID. At some point it changed from 6 mo TDY to a one year tour and NG and AR units are sometimes used.