Continuous flow refers to the amount of power that the PSU is rated to deliver constantly/for a indefinite amount of time. Lower quality power supply companies will usually inflate their numbers by labeling a PSU at the peak power, peak power being the amount of power the circuitry can deliver before it blows a fuse etc.
Oh no, it isn't constantly putting out that amount, that is what it is rated to continuously supply at that 40 degrees Celsius quoted in the item title. The power supply delivers power based on the computer components demand.
So most modern chips and components all have all sorts of power saving technologies such as gating (shutting power off to something completely), turbo boost, smart step etc etc that allow the components to use only the power required, cutting down on electricity used, heat generated etc etc.
If you had a power meter such as a kill-a-watt, multimeter or anything else hooked to your computer, power strip or anything, you would see the power being used constantly fluctuating based on demand. computer sitting idle = very little power used if the parts are efficient. Gaming/benchmarking/rendering = much more power consumed.