少年易老學難成 [－－－－学难－]

Jyutping siu3 nin4 jik6 lou5 hok6 naan4 sing4
Pinyin shào nián yì lǎo xué nán chéng

Definitions (Wiktionary)
  1. phrase, idiomatic
    if you do not study when you are young, you will grow old quickly without accomplishing much learning