Hebrew has no vowels so the spelling is just Yod(Y) He(H) Vau(V/W) He(H)
Jews thought it was blasphemy to say the name of God. Since they never said the name, people no longer know how to pronounce it.
Most people think it was pronounced Yahveh although it has previously been thought to be Jehovah.
When Jews speak about God they just say HaShem (the name).