What is the mechanism that transforms pressure into velocity?

I know it's a common question but I can't find an explanation that can clearly show how it happens. If we take Bernoulli's equation, being aware of its hypothesis, it states that energy is constant between 2 given points. So if pressure drops, velocity should rise.

I know flow mass should be conserved but one thing is the mathematical explanation and also the mechanism itself. How exactly does this happen? If velocity increases, should that be due to a force. Not gravitational not surface force so, which one?

Furthermore, if liquids can't be compressed and the temperature is constant. Where is this “pressure” energy stored?

EDIT: My question stems from working with hydraulic pumps in which diffusers are used to transform velocity into pressure.

It must have something to do with the geometry of the pipe but I can't understand how a liquid flowing with velocity drops some of it to increase its pressure in a wider segment of the pipe. More space should lead to less pressure and more velocity as it has more space available.

I am looking for a more “atomistic” answer such as this one (it doesn't satisfy me completely):

According to Bernoulli's principle, the pressure of a fluid decreases when its velocity increases (for e.g., in a nozzle). What is the physical reasoning for this?