What currency pair to trade — a Forex signal will always specify the currency pair to be traded.

What quantity to trade — you will need to know the number of Forex lots to be traded. 

How much capital to risk — knowing how much capital to risk on each trade is an absolute must.  Good Forex signals always give sufficient information in order to control risk. 

Which direction to trade — if you receive a bullish signal then you will want to buy it and if you receive a bearish signal then you want to sell. 

When to get in — this is the first component of timing the market. 

When to get out — this is the second component of timing the Forex market. 

Forex signals are generated by Forex trading systems.  Most of the Forex trading systems in use today come in the form of Forex trading software. Forex trading system software takes Forex data and uses this data to make the calculations which then generate the Forex signals. 

Good Forex signals can withstand the test of time.  This means that the signals will work in many different market conditions and this is important for the longevity of your Forex trading success.