You cannot inject external code into Roblox without breaking Terms of Service. However, players use the term "mod" to mean:
If you’ve ever wanted a volleyball game that captures the hype of Haikyuu!! — the quick sets, the feints, the thunderous spikes — this is it. The modded version (unlocked characters, infinite currency, no ads) elevates an already great game into a must-play for sports or anime fans. the spike volleyball mod
Downloading and installing The Spike Volleyball Mod comes with legitimate risks. Because the game developer relies on microtransactions, they actively patch exploits. Here is what you need to watch out for: You cannot inject external code into Roblox without