The Price Oscillator (PO) displays the difference between two moving averages of the security's price and attempts to assess the momentum of price activity, for a pre-defined time frame period.
The idea behind moving average analysis is that it generates buy signals when a short-term moving average (or the security's price) rises above a longer-term moving average. A positive PO indicates that the short term moving average is above the long term moving average. A negative PO indicates that the short term moving average is below the long term moving average.