Pressure is defined as the (orthogonal) force applied to a body per unit surface area and is given as:
Pressure = Force/Area
The units of pressure are Pascals (or Newton per square meter) in the SI system, psi (or, pound per square inch) in the FPS system or atmospheres (atm), or mm of mercury (torr).
Pressure is of importance to us in several day to day functions. An example is tire pressure, which is the pressure exerted by the air in the vehicle's tyre. Without this pressure, the vehicle's weight will not be supported by the tyres. The blood flows in our body under pressure, in closed conduits, without which we cannot survive. The gas supply to our homes, which is used for cooking and heating, is also a pressurized supply. There are numerous other examples of applications of pressure.
Hope this helps.