Are you learning English? Then you really need to learn the schwa sound. It is the noise that native speakers make more than any other.
But don't stress! Haha, that was my little joke. 'Don't stress' means something like 'do not worry', but when learning English, it also means 'do not emphasise every vowel sound'. The schwa is a sound that native speakers make instead of stressing every vowel sound.
For example, my name is Adam. Most people know that name, because I am named after the first human in the Bible. But a lot of people - particularly native speakers of Spanish, Portuguese, and Italian - pronounce my name like A-DAM. As a native English speaker, I pronounce it more like A-dum.
Watch this amusing video for more on the schwa. Learning it can make you sound so much more like a native English speaker!