pronunciation - How can native English speakers read an unknown word correctly?

I have learned English for many years, and from the first day I began to learn it I know the dictionary is necessary for the study. One of the important aspects is that English words, unlike German and Spanish, usually can not be read correctly without phonetics. But recently, I talked with some native speakers and they told me they can read any word directly and rightly even though they never learned it before. I just want to know how they can do that -- there is no ordinarily acceptable method to read an English word?