根据雅思大作文评分标准，你的词汇运用和语法结构的准确性方面做的不错，只是连贯与衔接及上下文的呼应方面有所欠缺，个人认为可以给6分，希望可以帮到你，继续加油，一定没问题的！
With the proliferation of English as a global language, increasing number of individuals are turning to learn English as their second language(此处改为second or foreign language为好，因为second language 和foreign language是有区别的，前者指的是除母语外的第二门语言，后者是除母语外的其它国的语言，如English对于法国人来说是second language而非foreign language,而对于中国人来讲是foreign language，如果你还有自己的民族语言，那么它就可能是你的third or fourth language了).Some people believe that the merits of speaking English overweigh the demerits while other are holding a opposite cognition.(cognition这一词汇用的太大了，cognition是认知，是语言学范畴，此处改为while others hold the opposite opinion) Ideed(Indeed)，the spread of English can bring us(us指代不明，可以去掉) astonishing impacts. (整体来讲，第一段还是没有明确指出你agree or disagree...，雅思的一条标准是回应题目要求，第一段干脆些，My viewpoint is./In my opinion,...开门见山)
Initially,we can have great access to learn about the culture of a foreign country through speaking English(through speaking its native language---English). As you know(人称一定一致，这个很重要，As we know),English is the most widely used language in the world. We can communicate with oversea people (in English)to know more about their country cilvilization(不是文明，改为文化，cultures,语言是文化的载体),by which （改为accordingly, ）we can treat them in a correct way respecting their culture(-s) and religions.(这一段还是稍显简单了些，论据不够充分，加一点对比结果效果更好：Only by this, may we avoid making stupid mistakes due to misunderstanding of their cultures and thus we do know what to talk and what to do when communicating with its people.)
In addition,master （mastering,动名词作主语）a English language （就是English）can also contribute to the national economy.For example,the prices of the labour in some Asian countries are low while it is really high in some Western countries .What''s more,each country has its speacial product,which is unique and be well-liked.They can benefit from the trade amomg the world.（这一段有点乱，论点论据都不突出，你认为劳动力价值的体现只是由于没有掌握好英语吗？不如改为：In addition, mastering English can also boost the learners'' national economy. For example, if we learn English well, we may cooperate more closely with western developed countries in all walks of life to obtain what we want, either funds or techniques. ）
Lastly(Lastly but not least, 最后但并不是最不重要的一点)，it can boost social stability and harmony with the ability of using English.If we can master English as our native language，we can know deeply about events and policy in different countries.(个人认为学好英语对国内社会稳定和和谐并无明显作用，它的作用在于和国外的和谐和交流)The further understanding of foreign countries can be advantageous to both authorities and individuals in the field of（in就可以了，本身这句话就太长了，简短一些） maintaining relationship with different regions and improving living standard（-s）through （bilateral）business trade.
In conclusion，learning English can provide people overwhelming (这个词有些夸张，毕竟你前面并没有给出相呼应的overwhelming..)number of benefits.（Undoubtedly, we can benefit a lot from English learning, as we can see above. ）(However,衔接词汇, it''s easier said than done. In view to this, constructive measures have to be done by the government.) In my point of view, The government should improve the schooling system of English learning in the field of communication to ensure our spoken English can keep pace with our written English.(最后一句话就没有呼应本文主旨，主旨是英语作为世界性语言推广的好处而不是重点在口语，如果你想侧重点在spoken, 那么前面一定要有所提及，否则此处显得唐突，你觉得呢？其实最后一句话可以改为政府应该有所作为，加大英语教育的投入和力度，避免英语作为应试教育的牺牲品，你也知道，现在大家学习英语大多为了应付考试，而非实际应用。所以，The government should improve the schooling system of English learning particularly in Spoken and Written aspects and should try not to make the English learning the victim of exam-oriented education。)