thank you ame, now I understand more and clairer my foults ! thank you very much ! :D

I will be a meddlesome and answer you :$ مفيد + جميل : masculine adjectives. مفيدة + جميلة : feminine adjectives. The plural of the feminine adjectives are : مفيدات + جميلات. لغات : the plural of لغة. But since that you are talking about "languages", which is not a humanbeing, the plural will be the feminine adjective. العربية والصينية والفرنسية لغات جميلة ومفيدة.

Thank you Ahmad, but there is one more thing that I couldn't understand why it is not same for " لغة", "مفيد" and "جميل". For exemple why not الصينية والعربية والفرنسية لغة مفيدة وجميلة ?