"Writing and translation" is very nearly a pleonasm (an unnecessary redundancy), at least in the case of business and technical writers. Granted, having the specific skills to translate a document from English to Spanish is incredibly useful, but even writers like myself, with only one language mastered, find ourselves translating whenever we are with a client. This translation is between the language of your client and that of his audience.
Let me give you a couple of examples:
Active Listening Skills
Rephrasing what your client asks you for is vital to successful business writing. You can't translate what you client wants if you don't listen in the first place. Avoid the vigorous nods to convince him you understand, and instead restate his concerns in your own words.
Business writers are translators as a matter of course. Go into every project with the understanding that even your client may not completely understand the scope and focus of the job and you will be able to better serve his needs.