A bike fitting is aimed at the most comfortable and efficient position for you on your new bike. You'll see the saddle up high enough to make you wonder if you can touch the ground while on it (toes of one foot MAYBE!), and lots of fiddling for what seems to be tiny adjustments. Trust -- they are necessary. Anyone who is any good at all with fitting while take some time, and make sure it's DIALED in. MILLIMETERS can make a big difference!
A lot of it is how you will FEEL on the bike; will you feel like you're sliding off front or back? (bad, BTW) Do you have pressure on your "taint"? (also BAD) Is there more weight/pressure on your hands than on your butt? These are all involved.
Basic maintenance tools are good thing, yes, but have little/nothing to do with fit; they just get mentioned because that's a good time to find out about them. A multi-tool, patch kit, spare tube, pump, tire levers, stuff like that is a good start. Ask how they work.
ENJOY THE RIDE!!