Hi, you know sometimes translation is not word for word, so the equivalent word for something varies under different context.
1.There is something in the room. 屋里有什么东西。someting= 什么
2.Something went wrong. 有些不对。 something = 有些
3. When we learn the English word something, our teacher gives us an explanation in Chinese which is "某个东西"。
I hope it helps.
If you are still confused, you can read more similar sentences, and you will use the word naturally.