How do I get Robux in my game?

Could you please elaborate on the process of acquiring Robux in my game? I've heard that Robux is a virtual currency used in Roblox, but I'm unsure of the specific steps involved in earning it. Is it possible to obtain Robux through in-game achievements, purchases, or some other method? Additionally, are there any restrictions or limitations on how much Robux I can earn? Clarifying these details would greatly assist me in understanding how to effectively accumulate this virtual currency within the game.