The numbers on the left of the graph are what's called the "base stats". They are pretty much the Pokemon's stat at level 50, without modifiers. So if a pokemon has base attack 80 and you catch it at level 50, its attack will be about 80.
The range on the right is the minimum and maximum at level 100. The stat at level 100 is approximately twice the base stat, plus modifiers.
The modifiers are things like nature, EVs and IVs.