Buys Ballot was a Dutch meteorologist wo lived from 1817 to 1890. He found out in 1857 that when he stood with his back to the wind, the low pressure system was on his left side, the high pressure system was on his right. And the high pressure system is always behind you, while the low pressure system is in front of you. This is only valid when you're on the Northern Hemisphere. On the Southern Hemisphere the effect is vice versa.
This rule is a combination of 2 laws:
Pressure gradient force: Air moves from high to low pressure systems.
Coriolis force: Air doesn't follow a straigh line, else the pressure on both of his sides would have to be equal.