The most important sentence in Judaism has no agreed English rendering, and the ambiguity is in the Hebrew rather than in the translators.
Six words, from Deuteronomy 6:4, and the difficulty is that biblical Hebrew has no copula, no verb "is" in the present tense, so the relationship between the four content words has to be supplied by the reader. The standard candidates: the Lord our God, the Lord is one; the Lord is our God, the Lord is one; the Lord is our God, the Lord alone; the Lord our God is one Lord. The Jewish Publication Society version prefers "the Lord alone", which makes the verse a statement of exclusive allegiance rather than of numerical unity.
That difference is not small. Read as unity, the verse is a metaphysical claim and has been used as such in polemic against trinitarian doctrine. Read as exclusivity, it is a covenantal demand, this God and no other, which fits the surrounding chapter, and fits a religious environment in which the existence of other gods was not in question but loyalty to them was.
The word rendered "one" can carry both senses, and the argument is old. Medieval Jewish philosophers, Maimonides among them, read unity and built on it.
The verse is followed immediately by the command to love God with all one's heart, soul and might, and to teach these words to one's children, speak them at home and abroad, on lying down and rising up, bind them on hand and forehead, and write them on doorposts, which is the origin of tefillin and the mezuzah.