The punctuation is wonky so it makes it a little difficult to understand. This is how I understand it: Yeah, [I am] very happy to have you. Prepare your stuff* because we are going to do many things. *Meaning: take the necessary gear/equipment. I don't know what you are planning to do. I hope it makes sense in your context.

So it means : yeah, i'm so happy to have you here (to your friend's place) = ouais trop content de t'avoir. Pack wisely ( take the appropriate clothes and things necessary to your stay) cause we are gonna do a lot of stuff together = Prépares bien tes affaires car on ira faire plein de trucs !

Yes, I am very happy to have a good preparation of your business, because we will go to do that stuff. Just for reference, thank you.

I think we could translate it like that : "Yes ! Very glad to have you here. Pack up your stuff, cause we are going to do lot of things." Hope I have been helpfull :)