A. Yusuf Ali:Translation:
We sent not a messenger except (to teach) in the
language 1874 of his (own) people, in order to make
(things) clear to them. Now Allah leaves straying
those whom He pleases: 1875 and guides whom He
pleases: and He is Exalted in power, full of Wisdom.

Muhammad Asad:Translation:
AND NEVER have We sent forth any apostle otherwise than [with a message] in his own people's tongue, so that he might make [the truth] clear unto them; 3 but God lets go astray him that wills [to go astray], and guides him that wills [to be guided] -for He alone is almighty, truly wise. 4
1874 If the object of a Message is to make things clear, it must be delivered in the language current among the people to whom the Messenger is sent. Through them it can reach all mankind. There is even a wider meaning for "language". It is not merely a question of alphabets, letters, or words. Each age or people-or world in a psychological sense -casts its thoughts in a certain mould or form. Allah's Message - being universal -can be expressed in all moulds and forms, and is equally valid and necessary for all grades of humanity, and must therefore be explained to each according to his or her capacity or receptivity. In this respect the Qur'an is marvellous. It is for the simplest as well as the most advanced.
1875 "Whom He pleases": the usual expression for Mashi'ah, the universal Will and Plan, which is All-Wise and on the highest plane of goodness and righteousness. (Cf. 16:93).