Phyllo dough is sold frozen. You can refreeze it if you remember to cover the dough with a damp cloth while it is thawed. This prevents it from drying out. Just wrap the phyllo sheets in some plastic wrap and place in a tightly-sealed freezer bag. The dough will keep for several months.
“Hi, I love to cook with phyllo dough, but I never use an entire box at once! Can you refreeze the dough?”