No, when there is full employment within the economy, it just
means that the economy is operating at full potential and it is
producing an output equal to the potential output.
It does not mean that, the unemployment rate is a perfect zero
when there is full employment.
This is because, when the economy is facing full employment it
is experiencing a natural rate of unemployment.
That is, there is still some amount of frictional and
structural unemployment present within the economy even when all
the output is fully employed.