Why is translating from one language to another so difficult?

All languages are different, not just in their sound, but in many other ways. Some don't have exact corresponding Words that others do. Rules of syntax and structure can vary, so you cannot do a Word for Word translation. Different Words in languages may sound the same or have different meanings, but that is not always the same in every language. Livre in French can mean both pound and book for example. Other languages would have different Words that sound the same but have different meanings. So context is important. Other things are important too, like pronunciation. All of these things and others, make translating difficult.