You know, sometimes several Chinese characters share the same pinyin and even the tone. ‘Jiayu’ sounds very moderate. It can be a girl's name or a boy's name. The difference is from different characters. For instance, if it is given to a boy, the name can be written as:
嘉宇（or佳宇） It means ‘universe’. It can be used to describe the open mind. wisdom and greatness of a man.
If it is given to a girl, it usually is written as
佳玉 (or 嘉玉) It means beautiful jade. It suggests that the girl’s parents hope their daughter is as beautiful and pure as jade.
There are many other written forms of the pinyin ‘jiayu’. I just wrote the above for your reference.