correction

Let's help each other.

Hi. I'm very happy to be here to help anyone in leraning Arabic. 
I need to improve my English because this language is the language of the business and sciences so I'll be happy if there someone want to help .

perhaps you mean:

I need to improve my English because this language is important in business and sciences. I'll be happy if there is someone who wants to help.

Let's help each other.

Hi. I'm very happy to be here to help anyone in leraning Arabic

I need to improve my English because this language is important in business and

sciences. I'll be happy if there is someone who wants to help.

Let's see.

Let's help each other

Hi I'm very happy to be here to help anyone in learning Arabic, 
I need to improve my English because this language (it) is important both in business and sciences. I'll be happy if there is someone want who are willing to help.

Keep stuying! Besides, I want you to teach me Arabic. :)