A Republic is just a state where important government offices (i.e head of state) is non-hereditary. A Republic just means something it not a monarchy.

That's all it is, the Soviet Union was a federated union of Republics, Islamist Iran became a Republic in 1979 from a Monarchy, China became a Republic when it overthew the emperor in 1911, France became a Republic when it overthrew the King in the 1790s.

Republic don't have to be democratic,. People just get confused because "America isn't a Democracy (yes it is), it's a Republic" gets brought up even though it doesn't even make sense. Syria is a non-democratic Republic, Britain is a democratic non-republic.

This would be a better question for /r/Ask_Politics