Hi Tatiana, excellent job! Your English is very good. I made a few corrections and suggested changes below in yellow.

Michael

Yesterday we visited a free lecture that was led by a British guy

Yesterday we visited a free lecture that was led by a British guy. The article (I would use lecture title here, article is more for newspaper stories) was 'How to be a lifelong English learner'. The idea of his lecture was that we can 'learn' a language and we can 'acquire' it.

When you learn grammar and vocabulary you feel that this is a hard work, and sometimes you have to force yourself to study. You can feel edgy and tense at that time, so it makes a the process unenjoyable.

On the other hand, when you receive new words like a newborn baby by listening and taking your time to understand it, you will get a more effective result. Even if you are relaxed in a bar with a glass of beer, you will absorb new language constructions better than in a class.
Actually, I know a one (only one or a is needed here, as both generally mean the same thing.)  man who can be would be the best example of this idea:-) (if you want to still use the verb can be, you could change the wording around to make it sound better, ex: can be described as the best example)

Honestly, I steel still can't believe that it works, yet I believe that by combining the two methods you can achieve your language goals.

Yesterday we visited a free lecture that was led given by a British/English man guy (guy is very informal - jiahuo)

Yesterday we visited a free lecture that was led by a British English fellow guy. The article was 'How to be a lifelong English learner'. The idea of his lecture was that we can 'learn' a language and we can 'acquire' it.

When you learn grammar and vocabulary you feel that this is a hard work, sometimes you have to force yourself to study. You can feel edgy and tense doing this at that time, so it makes the process unenjoyable. (don't like 'unenjoyable' - how about 'a struggle')

On the other hand, when you receive new words like a newborn baby by listening and taking your time to understand it, you will get a more effective result. Even if you are relaxed in a bar with a glass of beer, you will absorb new language constructions better than in a class.
Actually, I know a one man who can be the best is an outstanding example of this idea:-)

Honestly, I still can't believe that it works, yet I believe that by combining these two methods approaches you can achieve your language goals.