Q4: What are the words of Tawhīd (monotheism) and mention Tawhīd's meaning?

Answer: The words of Tawhīd are "Lā ilāha illallāh". This means that none is worthy of worship except Allah.

Allah Almighty says: {Then know [O Prophet] that none has the right to be worshiped except Allah...} {Surat Muhammad: 19]