Translation:He does not have children.
I'm not a native, and I can't say this applies in Chinese as much as Japanese, but essentially 子 means child as in 猫子 (kitten), 狗子 (puppy), and when written alone it can technically mean mouse when speaking about the zodiac signs. 孩 however, only applies to human children, especially babies and young infants. When combined, it's the Chinese compound for someone's child (ren), probably the same way 弟弟 and 妹妹 are 2 characters just because before writing, the word was 2 syllables. I'm not fluent though so please don't take this as the ultimate truth, just as an educated guess from years of studying 漢字