In English, some consonants are voiced like,.. and some are voiceless like,… So what is it mean to be voiced or voiceless? Listen to this… Now you can’t see the difference. You might be able to hear the difference. But, you can definitely feel the difference. Watch this…
When I make a voiced sound like /v/, my throat vibrates. Bur when I make a voiceless sound, like /f/, it’s just air coming through my mouth. Now you can also hear if you put your hands over your ears like this. When I make a voiced sound, /v/, it vibrates in my ears and my throat.
Now why is it so important? Because in English sometimes the only difference between a pair of words is one consonant voiced and the other consonant is voiceless. For example, van, and fan. Now you can practice this some more by watching the videos about voiced and voiceless consonants in the sounds of English section.