I get that with Bernoulli's Principle an increase in area = a decrease in velocity = an increase in pressure. I also understand the concept of pressure being force per unit area.
My difficulty is with understanding what is meant by pressure in this context. Is it the pressure exerted on the fluid from the pipe's walls (with an equal pressure exerted by the fluid on the walls)? Is it something else?
If it is the pressure exerted on the fluid by the walls of the pipe, why does it decrease when cross-sectional area decreases? I can see why from a mathematical perspective, that it occurs from how the formulae can be rearranged, but to me that just doesn't intuitively make sense. I just can't viscerally understand it, and a lot of how I understand things comes from visualising it, which YouTube videos unfortunately have not helped me with (as they explain how the formulae work, and I can see the decreasing area which in my head means pressure should increase [even though I can recognise it does not]).