The "Show Me / Tell Me (safety) questions" that you'll be asked on your practical test include some about important fluids in the engine-bay.
A driver is responsible for knowing they have enough (1) engine oil, (2) engine coolant, (3) brake fluid.
Coolant (expansion bottle) and brake fluid (reservoir) have MAX / MIN marks on the side. For the oil, use the dipstick.
Bonnet release lever is by the front passenger door hinge.