This refers to the force exerted by air weight on all surfaces around us. It's like being at sea level where there are many 'layers' of air above us applying pressure.
Pascal (Pa): This is the standard unit of pressure in International System of Units (SI). It's equivalent to one newton per square meter.
Boyle’s law states that for any gas at constant temperature, its volume inversely proportional to its pressure - just like how squeezing an inflated balloon decreases its volume while increasing its internal pressure.