Tawheed means that Allah is One. He has neither any colleague nor any partner. He is neither born of any parent nor has He any wife, children or relatives.
It means that God is Just. He is not a tyrant. Everybody's awards will depend upon his deeds. He who obeys His commands will be awarded a place in Paradise and he who disobeys Him will be sent to Hell.
In this connection, the Qur’an says:
“ALLAH affirms that there is no god but He: and so do the angels, and these endowed with knowledge, He is standing firm in justice”. (3:18)