Hello and welcome to JustAnswer!
What model is your vehicle, and which engine is in it?
Do you hear any engine noises when the oil light comes on?
Ok. Most likely you have a failed oil pressure sending unit. This is mounted right above the oil filter area. Often these will fail and leak oil into the electrical connector and the oil light will come on at stops when the pressure is naturally lower.
The first thing that should be done is unplug the oil sender and check the connector for the presence of oil. If there is oil in it the sender will need to be replaced and the oil cleaned from the connector. If the connector is dry then the sender should be removed and the oil pressure checked with a manual gauge to see if the pressure is actually low or not. If you don't have any engine noise and have kept up on maintenance in the past I wouldn't expect a true oil pressure problem, the 2.5 was a very good engine.