Frankfurt is a huge airport. It has gone from Terminal A to Terminal Z in the past. Now they're adding Terminals AA and BB to it.

Flying back from Zurich, it took close to 1 1/2 hours to get from Terminal A to Terminal Z.

Remember that you will have to go to the land side of whichever terminal you choose to meet in. This means going through passport control to get back to airside.

Good luck is all I can say.

rylea87, I would suggest you contact your travel agent or the airline you are flying with to find out which is your departing terminal.

Both Italy and Germany are in the EU so that flight isn't really "international".
You can Google for a site for the Frankfurt airport and locate your terminals. Probably you will want to meet her in the one you depart for Canada from so that you are located conveniently for departure.
Then pick a coffee shop or similar on the land side of the terminal and meet there. You will have to allow yourself enough time to go back through security and passport control.
I think it is perfectly do-able but you might want to check with your airline to see what they say.

Which airline are you using? I see both AirCAnada and Lufthansa have their check in at Terminal 1 but it is possible the gate could be in Terminal 2. There are 2 terminals, but it is a very large airport as Rasta says above and has gates all the way to Z.
I have been there a number of times and it is big and busy but there seem to always be lots of agents on hand to help you find where you are going.

Here's a map of the airport. There is a meeting point. You should find out where your connecting flight is so you can figure out how much time you need.

You should also check with your chaperones to make sure that they are OK with you leaving the group. They may not want to have you separate, particularly since they are responsible for you.

You should also have a plan of what to do if you miss your flight.

http://www.frankfurt-airport.com/content/frankfurt_airport/en/directions/airport_maps1/terminal_1_2.html

Your friend cannot come airside without a broading pass - so you will have ot go landside - which means taking the time to go completely back through security again.

I would get the details on your various terminals and also info on how often your incoming flight arrives on time. Allowing for all the toing and froing yuo might get to spend only 30 minutes or so with your friend. Is that worth it? What if you flight is late and there isn't time?

You will go through passport control regardless whether you stay airside and connect directly or make the detour landside to meet your friend.

While FRA may not score high on user-friendliness, it is no problem to do what you plan with 5 hours to play with. Just keep in mind what PPs said re. where to meet your friend.

The airport is not small, but it has not 26 Terminals A thru Z, but two separate Terminals (1 and 2), with concourses A thru E and Z. Only A and Z can be a PITA as they are quite long piers with a 15 min walk from security to the last gate. The other concourses are easier to handle and a much shorter walk from landside.

P.S.
You will go thru security regardless whether you connect directly airside or meet your friend. If your flight arrives on time, you can expect to be landside after 10-15 minutes after you left the plane as there are no controls to exit.