According to Wiki Guinep is
Melicoccus bijugatus, commonly called Spanish lime, genip, guinep, genipe, ginepa, kenèp, quenepa, quenepe, chenet, canepa, mamón, limoncillo, skinip, kinnip, huaya, ackee, or mamoncillo, is a fruit-bearing tree in the soapberry family Sapindaceae, native or naturalized across the New World tropics including South and Central America, and parts of the Caribbean.
I grew up eating guinep in the US only because my parents are Jamaican and they knew what guinep was.
According to the date on this article, Health Benefits of Guinep,
Guinep season in Jamaica, West Indies is in August. I do not currently live in Jamaica, so I do not know the exact season of when guinep comes about. I must say Jamaica is a beautiful island and this fruit is a great snack. At the moment, I love that it helps with weight loss!
Check out the highlighted link above or here (Health Benefits of Guinep) for the actual health benefits and also when and if you give his fruit a try, DO NOT SWALLOW IT! Just bite off the soft flesh on the outside of the hard seed covering.
Enjoy the summer!