The logic rule "Indicator rises" means that when the current indicator value is higher than the previous value, the program rises a buy signal. When the current value is lower then the previous, the program rises a sell signal.
The logic rule "Indicatior falls" is opposite - when current value is lower than the previous one, the program gives buy signal and when the indicator goes upwards, we have a sell signal.
You have to be careful when "Use previous bar value" option is on. In that case the signal is shifted on bar ahead.