these are standard fields which you can see in MRP views when you extend/create your materials with MRP views. create a material with MRP1, 2, 3 fields and you will see these fields there, you need to maintain the relevant qty in these fields, like what qty for that material should be re-order point, what should be minimum safety stock.
go to below thread to understand about re-order point
http://help.sap.com/saphelp_46c/helpdata/en/f4/7d256344af11d182b40000e829fbfe/content.htm