If I control Zilean and Leblanc legend and I copy to make a reflection copy of Zilean, how many Zilean will I make, 2 or 1 and a reflection token?

You get 2 Reflection tokens, both of which become copies of Zilean. So you end up with your original Zilean plus two copy-Zileans — 3 total units with Zilean's stats and text.

Here's how it works (per official FAQ #9917):

1. You conquer/hold, exhaust Deceiver, discard 1, and the ability resolves.
2. It tells you to play one Reflection token — but Zilean's replacement effect kicks in, changing that to "play that token and an additional copy."
3. Two Reflection tokens enter the battlefield ready.
4. The Deceiver's reflexive trigger then resolves, making both tokens become copies of Zilean (and giving them Temporary).

No infinite loop — after the two tokens enter and become copies, there's no new "play a token" event for them to replace, so the chain stops there.