A hydraulic press consists of two pistons of different sizes.

The space between the two pistons is filled completely with a liquid, usually hydraulic oil.

When a force is applied on the smaller piston, the pressure exerted on the liquid at the smaller piston is transmitted equally throughout the liquid.

Hence, the same pressure is also exerted at the bigger piston.

Since P = F/A, the F/A ratio will be the same at both pistons.

Since A1 < A2, hence F1 < F2.

So a smaller effort on the smaller piston (F1) will be able to lift a bigger load at the bigger piston (F2).