I encountered this statement that the dark side of the moon is hidden from our sights. Could someone please explain?
Yes, the dark side of the moon is mostly hidden from earthbound observers. This is due to tidal locking:
A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This causes one hemisphere constantly to face the partner body.
In other words, one moon-year is just as long as one moon-day.
The left-hand side shows the actual configuration of earth and moon: The orbit is locked and we can only observe one side of the moon. On the (fictional) right-hand side, the moon does not rotate around itself and we can observe different areas of the moon at different times.
I should note that we can actually observe not 50%, but around 59% of the moon's surface because of libration and parallax effects that cause the moon to slightly "wobble":