U has 3 sounds in English. The most common is "uh" as in: but, jut, luck (this is rather like the "shwah" sound in English. The next most common sound for U sounds like the word "you". The sound is demonstrated by the word use, mute, puke, reputation. (Here the U joints with the previous consonant. The third most common sound for U sounds like U as in put. .

say look, pull, full, soot, foot