Do you mean public school or private school? For private school, there would be a wide range.
Public school for Primary education is free, like in the US. Primary is kindergarten through 6th grade. "Free" is somewhat of a relative term, like it is everywhere, as there are costs for shoes, clothes, lunch, book fees and ancillary items.
Secondary education is 7th through 11th grades, plus 12th and 13th for university-bound students. Secondary education is not free. However, there is wide disparity both in school costs/fees, and what parents actually pay. There are various government programs and subsidies which may help. In general, fees will run JA$5000 to JA$20,000 per year. This is between about USD $60 and USD $250 per year. Again, these are school fees, and may or may not include book rental and insurance, and will never include clothes, backpacks, etc.
Seem reasonable? Just don't forget that the per capita income in Jamaica is about USD $7500, so $250 would be almost half of one month's gross earnings for the average wage earner.
In other words, if you have the opportunity to help a Jamaican child go to secondary school, you can really make a difference without a whole lot of money.