Khatura, or more specifically, the pollen of the Khatura flower, is a red powder that is a very strong and addictive narcotic. Little is known about it, other than that it originate on the planet LV-363, where it is harvested by shadowy corporate interests for (presumably) shadowy corporate purposes.
But since the planet is now over-run with xenomorphs seeded there by the Yautja, it’s unlikely that any humans will be sampling Khatura again any time soon.