The "Long Jack bitters drink" is typically a locally produced herbal beverage, popular in Southeast Asia and parts of Africa, that uses Eurycoma longifolia (Tongkat Ali) root extract as its primary ingredient and is primarily marketed for male vitality. It has a characteristically bitter taste. 
Key Details
Primary Ingredient: The main component is Eurycoma longifolia jack root, also known as Tongkat Ali or Longjack. Other ingredients may include Halban bark, honey, dates, black seed, and various vitamins and minerals depending on the specific product (e.g., the Orang Kampung brand LongJack Juice).
Taste: The extract from the Tongkat Ali root has a distinctly bitter taste, which is why products containing it are often referred to as "bitters".
Form: It's available in various forms, including pre-mixed drinks, liquid tinctures, powders, and capsules. 
Reported Benefits and Traditional Uses
The ingredients in the Long Jack bitters drink have been traditionally used for a variety of purposes, though more extensive research is needed to confirm many of these effects. 
Male Health: It is most widely used to enhance male libido, improve erectile function, and potentially increase testosterone levels and male fertility.
Energy and Vitality: Users report an increase in energy levels, a reduction in fatigue and drowsiness, and improved focus/concentration.
General Wellness: In traditional medicine, it has been used to treat a variety of ailments, including body aches, high blood pressure, diabetes, anxiety, and malaria.
Athletic Performance: Some evidence suggests it may boost athletic performance and increase muscle mass, likely due to compounds called quassinoids.