okay so i have a relay module that i want to connect to my lights in my room and i'm wondering if i can have it connected to my light switch and the relay module?
Thanks in advance.
Yes, parallel to the light switch.
If you want both the relay and switch to operate the lights regardless of the other, you might need multiway switching : Multiway switching - Wikipedia
a safer way
I like to remove the switch from the ac and make it in input for the arduino. Allows you to do more cool stuff 
Just be sure to wire it right as in don't leave any ac stuff hooked to it lol.