An online resource that I use to look up Greek passages and their pronunciation can be found at Crosswalk.com. This site offers a Hebrew and Greek interlinear version of the Bible.
For example, I was recently looking up the use of the word Dunamis (power or great force) for a Bible study lesson and used Crosswalk.com to translate Acts 1:8 and 19:11. I was then able to see the English version above the Greek. By clicking on any Greek word, you are then taken to a page which provides both a definition and a short audio clip of someone pronouncing the word.
Crosswalk.com also has a wide variety of Bible study resources, from devotionals and music to the latest news as it relates to Christians.
Have a blessed, safe and happy weekend!