‘He also made posts of sixty cubits, and the court to the post, the gate round about. And from the forefront of the gate at the entrance to the forefront of the inner porch of the gate were fifty cubits'
The sixty cubits would be the gateposts at the outer end of the gate, forming a deliberately imposing gateway, common in antiquity. It was what those who were without would see. The phrase ‘and the court to the post, the gate round about' is a little obscure and may mean that the distance between where the court was entered (the inner gate), and the outer gate was filled by the whole gate construction, the distance being fifty cubits, or it may signify that the outer court came up to the gateposts, externally to the gate itself, at each side of the gate, but of course inside the walls, as the gate construction would protrude out into the outer court. Either way the length of the whole of the construction of the gate (from outer gate to inner gate) was fifty cubits.
The whole intention is to give the impression of a magnificent gateway protecting the way into the temple precincts (lest the temple be defiled), and manifesting the glory of God.