A detailed changelog of the new firmware is currently unavailable, but it should bring in One UI to the Galaxy A8s along with other niceties of Android Pie. The update is rolled out in China over-the-air with April 2019 security patch.
The Samsung Galaxy A8s debuted last December sporting a 6.4-inch FHD+ Infinity-O display. It's powered by Snapdragon 710 SoC and has a triple camera setup at the back which is a combination of 24MP main, 10MP telephoto, and 5MP depth sensing units.
Apart from China, Samsung sells the Galaxy A8s in South Korea as well, but under the moniker of Galaxy A9 Pro (2019).