The ו indicating "and" does not usually have a vowel. However, it might receive one when the first consonant in the word is also vowel-less,to avoid double letters with no vowel.
At times, this means "ve" turns to "oo".
In addition, the letter כ has two sounds - /k/ and /kh/. the difference is grammatical, so adding a letter before it may change its sound.
Both together account for what you hear.
I think hebrew makes sense for me, but sometimes like that phrase above make me strugle to catch what does the things work in this language, I'm not saying I will give up on learning hebrew. Sometimes I heard: עכבישים=akavishim, akhvishim=צבים tzavim, tzabim. For God's sake what do it work because it's killing me.