Zn(s)|Zn²⁺||Cu²⁺|Cu(s)

In the external circuit, the electrons flow
from the zinc electrode to the copper electrode.

The half-reactions are:
Zn Zn²⁺ + 2e¯ (as the zinc electrode is negative)
Cu²⁺ + 2e¯ Cu (as copper is the positive electrode)

the overall reaction is the sum of these,
Zn + Cu²⁺ Zn²⁺ + Cu