Maple Syrup is one of the three basic Player Needs that you need to look after to survive; it can be thought of as the game's thirst meter. Kali-Gas stocks 21 bottles of it per day, and they can be purchased for $7.00 each. The player can also make and seal their own Cans of syrup in the Sugar Shack, but doing so requires buying the necessary equipment.
It can also be used as a source of income. If the player can make enough syrup to fill a Barrel, it can be sold to the Maple Syrup Federation for a tidy sum of cash: $200 instantly, and $200 per week for the next 5 weeks, payable on Sundays. One full barrel of syrup will pay the player $1,200 in total. Many players chain this effect for multiple barrels over multiple weeks, resulting in weekly paychecks in the tens of thousands of dollars. A more in-depth explanation on how this works can be found on the Barrel page.