If it's not obvious after a few tries at pronouncing it. Kuesuto translates directly to Quest in English. This website is dedicated to the quest to better understand Japanese(Nihongo).
You may notice that kuesuto and quest sound pretty much the same. This is an important observation. Roughly 10% of the Japanese language is comprised of words that were integrated from English. So you are already a tenth of the way to speaking it!
On that topic, the Japanese language has a special set of characters that are used in cases such as this, it is called Katakana. It is reserved just for words that did not originate in Japan. This method of distinction is important to understand, because they have a different Kana for words that are Japanese, it is called Hiragana.
Kana are syllabic Japanese scripts, which represent the sounds and vocalizations of the language. A bit different that letters, or characters, the Kana scripts are meant to allow pronunciation with out the need to memorize the thousands of Kanji characters which represent entire words or concepts with one character.
Phew. That is a mouthful. Rest assured the tools on this site will help you to get a quick grasp on the Kana Scripts and their uses.