The Moon's rotation and its "near side" always facing the Earth are due to a phenomenon called tidal locking. Tidal locking occurs when the gravitational forces between two objects cause one object to consistently face the other, keeping the same side always pointing toward the more massive body.
Here's an explanation of both aspects:
Tidal locking and the "near side" of the Moon: The gravitational interaction between the Earth and the Moon has caused the Moon's rotation to become tidally locked with its revolution around the Earth. As a result, the Moon takes about the same amount of time to complete one rotation on its axis as it does to complete one orbit around the Earth, approximately 27.3 days. This synchronization means that the Moon's rotation period is the same as its orbital period, so the same side of the Moon always faces the Earth, which is known as the "near side." The far side, or "dark side," of the Moon refers to the hemisphere that is permanently hidden from Earth's view.
Visibility of the far side of the Moon: Because the Moon is tidally locked, the far side remains unseen from Earth unless observed from spacecraft or satellites that have been sent to orbit or fly around the Moon. It wasn't until the Soviet spacecraft Luna 3 in 1959 that we obtained the first images of the Moon's far side. Since then, several other missions, including the Apollo missions, have provided more detailed observations and mapping of the far side.
In summary, the Moon's lack of rotation on its axis and its tidal locking with the Earth's gravitational pull explain why we only see the near side of the Moon from Earth and why the far side remained hidden until space missions allowed for direct observations.