ok, so AMA is one of the core functions in BenQ Gaming Monitors, especially the RL series, in the fact that its one of the 3 things that allows our gaming monitors to be so low latency, among the instant mode and TN panel(~1ms GTG response time). AMA stands for Advanced Motion Acceleration and it is a part of different functions that are responsible for RTC (Response Time Compensation). What enabling it does is that it drives more voltage to the liquid crystals so that they would align into place to produce an image much faster than with it being off (all of these amounts are miniscule, but still makes a noticeable difference). For example, a TN panel is rated by the manufacturer (SHARP, AUO, etc.) to have 5ms response time. AMA reduces that to ~1ms.
This allows the panel to have reduced trailing and motion blur from fast action scenes, especially useful when you are gaming on a console. This also has very positive side effects at 144hz if your monitor does not have dedicated motion blur reduction functions in the menu.