SMA is used both in combination with other indicators and independently.
If the SMA is rising, then the trend is bullish. It’s better to open Up trades.
When the chart crosses the indicator going upwards, it is probably signaling an uptrend.
If the SMA is falling, then the trend is bearish. It’s better to open Down trades.
When the chart crosses the indicator going downwards, it is probably signaling a downtrend.