Throwables are a type of weapon in PUBG
The throwable weapon type is perhaps the most consistently misused in the game. While they can do immediate damage, they're best used as a denial weapon. By laying down fire and tossing these weapons into an area, you're denying this area to your adversary, allowing for greater control of their movement and their basic abilities. For instance, the Smoke Grenade can help obscure your movements ,and the Stun Grenade can help to remove sight and sound from your adversary, at least temporarily.
Source: https://pubg.gamepedia.com/Throwables