Casual:
Yeah, sure. Here you go.
No problem! I’m always happy to help.
Yep! I will be right there. (Yep is another informal way to say yes like yeah.)
Yeah, I’d be happy to!
You got it.
Okay.

Professional:
Yes, of course. I will get it to you this afternoon.
I’d be glad/happy to make reservations for you.
Absolutely. I will finish it this afternoon.