As a general answer, just call Head on an interesting value returned from the function.
Let's look at GE...
ge = FinancialData["GE", "OHLCV", DayPlus[Today, -10]];
ge // Head
returns
TemporalData
The documentation for Temporal Data tells us how to pull the data out. For example:
ge["PathComponents"]
returns a list of 5 TimeSeries. Unless things have changed (which they might have, so please verify), I believe that these TimeSeries are the Open, High, Low, Close and Volume data, in that order.
When I was looking into this a few months ago, I spent a lot of time digging into the docs of TemporalData and TimeSeries.
Good luck.