"Please show me today's homework."
It's a particle - in this sentence it sort of acts as the " 's" in "today's". The meaning of this particle (like most others) changes depending on context. It's often interpreted as "belonging to" (e.g. my friend's dog = 友達の犬/ともだちのいぬ), or can be used to indicate the position of something in relation to something else (e.g. behind me = 私の後/わたしのうしろ).
Can you copy exactly what you've written into a comment here so we can take a look?
Maybe you had a typo, forgot a word or particle. No offense, but you also forgot the "am" or "'m" between "I" and "typing", as well as using the possessive "its" instead of "it's", so maybe you've done something similar in your Japanese sentence.