As above, they are called pawls and allow the freewheel to act as a one way clutch. They lock the outer shell (with the cogs) to the the inner core (attached to the hub) when you pedal but come out of engagement and let the wheel continue to roll when you stop pedaling.

If the reassembled freewheel doesn't work properly, replace it with a new one. For all practical purposes repair parts aren't available and new complete freewheels are so inexpensive that, except as a curiosity, they are rarely repaired or even disassembled for cleaning.