Traders use moving averages to spot initial signs of trend, both on the upside and on the downside.
One of the most common trading strategies is to catch the crossing of a fast moving average (calculated based on fewer periods) with a slower one (using a larger number of periods).
A crossing usually signals a potential trend reversal, which can provide excellent opportunities for traders.
When setting up a condition to trigger when a moving average crosses below or above, the system will wait for the confirmation of the values based on the most recent closed candle.
Once a crossing event occurs, it is considered valid until the new candle closes.
This video provides more explanation.
Waiting for the confirmation of the signal, instead of triggering the trade immediately, prevents from getting buy and sell orders multiple times within a short period of time. This part of the "patient approach" you should always incorporate into your trading systems.