I would like to apply for the job of a bartender as advertised in this week's issue of Throughout the World.

I have some experience of tending the bar. It should be mentioned that I have been working in this sphere for the last twelve months. This position would give me a good opportunity to enhance my professional growth and share my experience with other colleagues. There are a number of specific skills that I could offer as a member of your personnel team (personnel is not technically incorrect, however team is a better word). I have a great a lot of experience in mixing and serving drinks to satisfied and am able to satisfy even the most any critical customer. Moreover, my knowledge of English provides allows me with the ability to recommend a suitable foods and beverages and in addition calmly respond to agitated guests. My stamina allows me to work long shifts and help other bartenders during rush hour.

I feel that I have necessary character traits for this position. I am dependable, am able to multitask and I am adaptable to rapidly changing circumstances and.

I hope you will consider my application. I look forward to hearing from you.

Your sincerely,

Liubov

Your english is actually very good, there was nothing that I did not understand and your grammar was pretty good. However, my only comment to add to this, is that it is a very formal application for a Bartender role, a Bartender while requiring all the skills you have listed above is also very dependant on personality, unless of course you are applying for a very upmarket, formal position. In the above your own personality does not come through. So, if this is a real cover letter, you may find it beneficial to talk a little about you. - Good Luck!

Dear Mr Peabody,

I would like to apply for the job of a bartender as advertised in this week's issue of Throughout the World.
I have some experience of  in tending the bar. It should be mentioned that I have been working in this sphere profession (or capacity, or area,) for twelve months. This position would give me a good opportunity to enhance my professional growth and share my experience with other colleagues. 

There are a number of specific skills that I could offer as a member of your personnel. I have a great  lot of experience in mixing and serving drinks to satisfied  that will satisfy any critical customer. Moreover, my knowledge of English provides me with the ability to recommend a suitable food and beverage or calmly respond to agitated guests. My stamina allows me to work long shifts and help other bartenders during rush hour.
I feel that I have the necessary character traits for this position. I am dependable, able to multitasking ,  and adaptable to rapidly changing circumstances. and I hope you will consider my application.
I look forward to hearing from you.
Yours sincerely, 
Liubov

Good job! This is easy to read. 

https://owl.english.purdue.edu/engagement/2/1/45/