It tells the expected value of each property.
I tried making one myself in real life but it is pretty boring. What I did was set up four pieces and rolled the dice for each piece and then wrote down where they landed. I figured the average game has 40 rolls so I did that. That is only 160 observations though.
The chart doesn't always help...and different groups have different rules. For instance, my parents play by the rule that once a person owns one of a color group no one else can own it. The chart helps out greatly there.
Another scenario where the chart helps is the auction method, where each property is auctioned off after someone lands on it. That way every property is owned quickly. The strategy varies a bit here, as the initial person gets the best deal and someone ends up overpaying and risks capital strangulation (they don't have enough money to improve their properties) From my understanding, this is in the actual rulebook.
And yet another way to play is where anyone can own anything (like the auction method) yet, there is no auction. That is a gay way to play and I don't do that. None of my strategies are much good.