Strategy period is based on bar or ticks. Bars or candlesticks are composed of OHLC values (Open, High, Low and Close). Each bar represent a time period which can range from a minute to daily bars.
When a strategy is created the desired period can be selected.
Note that when cloning a strategy from the designer the period can be changed.
After the strategy is created the period is visible on the on top left corner represented by a blue box.