Well, it depends on which surname Wang you refer to. I mean, there are four Chinese surnames that could be written in Pinyin as Wang, i.e., 王, 汪, 望 and 旺. Of course, precisely speaking, 王 is written in Pinyin as wáng. 汪 is written in Pinyin as wāng. 望 and 旺 are written in Pinyin as wànɡ. But on many occasions, tones of Pinyin are omitted.
Here is a picture showing how to write a Chinese character 王.
Here is a picture showing how to write a Chinese character 汪.
Here is a picture showing how to write a Chinese character 望.
Here is a picture showing how to write a Chinese character 旺.
If what you refer to in this question is the surname 王, then this Chinese character indeed could mean king. If what you refer to in this question is the surname 汪, then this Chinese character could mean vast. If what you refer to in this question is the surname 望, then this Chinese character could mean hope and expect. If what you refer to in this question is the surname 旺, then this Chinese character could mean prosperous.