Judaism holds that God is one in a sense that admits no division and no parts. The Shema, Shema Yisrael, YHWH eloheinu, YHWH ehad, "Hear, O Israel: the LORD our God, the LORD is one" (Deuteronomy 6:4), is recited twice daily and is the nearest thing the tradition has to a creed. Maimonides made the point technical in the second of his thirteen principles and in the opening chapter of the Mishneh Torah: the unity of God is not the unity of a body made of parts, nor of a species with members, but a unity unlike any other unity that exists; God has no body, no bodily form, and nothing in creation can be compared to Him.
The four-letter name YHWH, the Tetragrammaton, is written in the Hebrew Bible some six thousand times and is not read aloud. The reader substitutes Adonai ("my Lord") in liturgy and HaShem ("the Name") in ordinary speech. The Mishnah records that the High Priest pronounced it in the Temple on the Day of Atonement and that the people prostrated themselves when they heard it, and it preserves Abba Saul's ruling that one who pronounces the Name according to its letters has no share in the world to come. After the destruction of the Temple in 70 CE the pronunciation ceased to be transmitted and it is not recoverable. This entry records the restriction and does not attempt a pronunciation anywhere.
The vocalisation Yahweh is a modern scholarly reconstruction from Greek transcriptions in the Church Fathers, not a Jewish usage. Jehovah is a different thing again: a hybrid produced by reading the consonants of YHWH with the vowel points the Masoretes attached to them to cue the substitute word Adonai. It became current in Latin and then in the European vernaculars from the sixteenth century, and no ancient Israelite ever said it.
The other names work as descriptions rather than as the Name. Elohim is grammatically plural and takes singular verbs when it denotes the God of Israel. El Shaddai, El Elyon and El Olam are patriarchal titles; YHWH Tzevaot, the LORD of hosts, is the martial one. Ehyeh Asher Ehyeh, the self-designation at the burning bush (Exodus 3:14), is rendered "I am that I am" and, with equal warrant from the Hebrew, "I will be what I will be".