It's not that bad. The words will notIt won't change their meaningsyour words' meaning, and in some cases you will, it'll possibly be understoodmake you even bettermore understandable. If you areyou're a novice language learner, I suggest just you forget about vowel reduction.
One example areis the words кампания "campaign" and компания "company". With vowel reduction they are indistinguishable, so to be understood correctly, you may, in some cases, pronounce the first vowel without reduction. Another example is маток "small mat" vs. моток "skein".