(으)ㄹ 것 signifies future tense
Check out noun modifiers V+는/(으)ㄴ/(으)ㄹ for more info.
In casual or colloquial language, 는 것 is often shortened to 는 거. Spoken language transcribed to text may often be written this way.
Native speakers often colloquially write 는거 (without the space). It doesn't strictly follow spacing rules, so its a common "mistake". The meaning is the same.