Pascal is unit of pressure SI. Pascal has the dimension kg/MS2. 1 Pascal is the pressure exerted by a force of 1 Newton on a 1 m2 area.
1 mm Hg is a non-system unit of pressure it applies to pressure of gases: the atmosphere, water vapor, vacuum. The name describes the physical essence of this unit: the pressure on the base of the mercury column of 1 mm height. In a precise physical definition of a unit includes also the density of mercury and gravitational acceleration.
1 mmHg = 133,322 N/m2 or 133 PA. Thus, if we speak about the pressure of 760 mmHg, the PA will receive the following: 760*133,322 = 101325 PA, or about 101 kPa.