What is a sustained break?
A "sustained break" means a break that has staying power above or below a certain support/resistance level, and is used as confirmation of the trade in the direction of the break. How you define "sustained" depends on your trading strategy and how strong the trend is. Many daily traders look for a close above or below support/resistance levels on their main trading timeframe. After a break of resistance that level becomes support and after a break of support that level becomes resistance.
For example if you trade primarily from a 60m timeframe and are looking for long positions (trend is up) you might look for a close above a pre-defined resistance level on the 1h charts. If the trend is very strong you might settle for lower timeframes such as 30m, and if the trend is weak you might look at the 2h or 4h charts.
In very weak trends or for a very conservative strategy you might look for consolidation above your resistance level or below your support. Consolidation shows as several candles that close past the broken level without piercing back down. This shows that bulls and bears are more or less in agreement (equal buying to selling) at that level and that the break was not false.
A disadvantage to this strategy is that in strong moves you sacrifice a better entry price for more confirmation, and this is something that must be balanced with your particular strategy/analysis. An alternative that will get you a better entry price but produce less signals is to wait for a pullback or throwback to the original break point. For example if you are looking for shorts below 1.2050 you would wait for a sustained break below 1.2050 and then set a sell entry around 1.2040-1.2050 to capture a potential pullback to the area.
Read more about pullbacks and throwbacks