Just about every English chumash and siddur translates the first verse of the Shema as "Hear O Israel, the Lord our God, the Lord is one." Artscroll has it as "Hear O Israel, Hashem is our God, Hashem the one and only." In his recently published prayerbook, Chief Rabbi Jonathan Sacks translates the first word as "listen" rather than "hear", so the whole sentence is "Listen, Israel: the Lord is our God, the Lord is one." (And he omits the unnecessary word "O"!) He explains his translation in the commentary to Shabbos Ma'ariv (pp. 277-278):
Shema means not only to "hear" but also "to listen, understand, internalise, respond and obey." It is translated here as "Listen" because listening is active, while hearing is passive. This, the most famous line of Jewish prayer, is a call to action on the part of the mind, emotion and will. It asks us to reflect on, strive to understand, and to affirm the unity of God. God speaks in a "still, small voice", and to serve Him is to listen with the totality of our being.
Secular terms for understanding are permeated with visual images. We speak of insight, foresight, vision, observation, perspective; when we understand, we say "I see". Judaism, with its belief in an invisible, transcendent God, is a culture of the ear, not the eye. The patriarchs and prophets did not see God; they heard Him. To emphasie the non-visual nature of Jewish belief, it is our custom to cover our eyes as we say these words.