What is meant by "spin = 1/2" for elctrons? DOes it have anything to do with the spinning of electrons?What is the physical significance of the quantity "spin quantum number"?
Spin = ½ of an electron is a quantum number. This number is like an address of the electron. It comes from the Pauli’s Spin matrix.
There is no classical analog for the spin of an electron.
You shall learn about the quantum numbers in higher classes.