A 500 general exp is an item in Evony TKR (The King's Return).
The description of 500 General EXP in Evony TKR says:
Grants your General 500 EXP.
500 General EXP is known to potentially be obtainable from opening Lv1 Boss Monster Chest, Lv2 Boss Monster Chest, Lv3 Boss Monster Chest, Lv4 Boss Monster Chest and Lv5 Boss Monster Chest. The links for each item are below:
Note: This list may be incomplete.