Before every round of golf in every golf tournament of significance -- pro, amateur or otherwise -- around the world, the players are handed a pin sheet. The pin sheet tells the players competing where the hole is located on each of the 18 holes (or 9 holes) during a stipulated round.
The pin sheet shows all 18 greens. Depending on who is putting on the tournament, the green diagram for each hole may be pretty close to exact, or it might basically be a circle. Either way, on the diagram, there are two lines which meet at a right angle, and there are two numbers.
The number along the line running from front to back of the green diagram is how many paces from the front of the green -- as measured by the very front of where the green is deemed to start -- the hole location (pin placement) is on the green. The more paces on the diagram, the closer the hole location is toward the back of the green.
The number along the line running from one side of the green diagram to meet the other line tells you how many paces on from the left or right edge of the green the hole location is on the green. If the line starts from the left edge, this number measures paces from the left edge, and vice versa from the right edge.
If you see a hole location less than 5 paces from the edge of any side of a green, it's a professional-grade, difficult pin position. More than that, the hole location is probably fair for most players.