If you're a male, and have dark facial hair which grows quickly, you're likely to get a "five o'clock shadow". This means you look as if you need a shave by 5o/c in the evening.
The other part you need to know here is the verb "to wax". It means "to remove unwanted hair from the face or body by means of applying strips of hot wax, etc."
It's a little difficult to guess the meaning of your dialogue out of context, but it suggests:
Russell: Book me a hair-removal session at Burke Williams. Ask them to book Janette as my hair-removal operative.
Maggie (incredulous, since it's more usual for women to "wax"): You remove unwanted hair by means of a wax treatment?
R: It's not a full wax. The hair has begun to grow back.
M: Oh Jesus.
It isn't clear from the dialogue whether Russell has unwanted hair on his face or body; but I would suspect the latter.