what physical property of water and HCl allows us to seperate them from the zinc chlorine produced in the reaction?

The physical property is the "boiling point".

The reaction between zinc and HCl gives zinc chloride solution and hydrogen gas.
Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

Normally, HCl is in excess, and zinc is the limiting reactant/agent which completely reacts. Besides, hydrogen gas escapes away during the reaction. Therefore, the final reaction mixture contains water, HCl and zinc chloride.

Zinc chloride is an ionic compound, while water and HCl are molecular compounds. Therefore, zinc chloride has a much higher melting point than water and HCl. Heat the reaction mixture to boil off water vapor and HCl gas, the solid left is zinc chloride.