There are two types of water pump that can improve your water pressure: a mains booster pump or a shower/whole house booster pump. Both of these will increase your water pressure and flow.
A mains booster pump is fitted to the mains supply of water and will generally improve the water pressure across your whole property.
A shower/whole house booster pump, however, is an individual unit that boosts the water pressure of a particular outlet. It can increase the speed of filling a bath, boost the performance of your shower and improve the time taken for your toilet cistern to fill. An example of this type of pump is a HomeBoost pump.