I am not sovery good in eat English conversation because of my lacking of vocabulary and grammar knowledge.

But it's better if you say something like "because my vocabulary and grammar are limited" or something like "because i lack vocabulary and grammar", also you need to use "at" if you're talking about being good at something

Could any body suggest me how to improve it.

I am worried about my English communication skills because it hitimpacted my promotion.

impacted or affected maybe

I am not so good in eat English conversation because ofI lacking of an extensive vocabulary and understanding of the grammar.

Could any body suggest to me how toI could improve it.

I am worried about my Englishability to communication because it hie in English as it will affect my promotion.

I am not so good in eat English conversation because ofI am lacking of vocabulary and grammar.

Could any bodysomeone provide suggest meions on how to improve it.?

If you want to emphasize conversation then "Could someone provide suggestions on how to improve my conversation skills?" Or if you want vocab/grammar then "Could someone provide suggestions on how to improve my vocabulary and grammar?"

I am worried about my English communication skills because it hitimpacts my promotion.

If you are not going to get a promotion, then ".... because I won't be promoted." If you are worried about work in general "...because it affects my job opportunities." or "... because it impacts my career."

I am not so good in englishat having conversations in English because ofI'm lacking ofin vocabulary and grammar.

Could any body suggest to me how to improve it.?

Alternatively: "Could anyone give suggestions on how to improve?"

I am worried about my English communication because it hiwill affect my promotion.

I'm not sure what you meant by "it hit my promotion". Do you mean that it will affect your promotion, in the future?

I am not so good in eat English conversation because ofI'm lacking ofin vocabulary and grammar.

Could any body suggest to me how to improve it.?

Keep practicing! You’ll get there :D