He has a timid personality and is afraid to try new things.
It is sometimes said that timid people are not suited to be leaders.
Standard kanji spelling for this word.
Kana spelling is acceptable, especially in casual writing or when the kanji is not needed.
Composed of 小 (small) and 胆 (gallbladder, courage). The combination suggests 'small courage', i.e., timidity. The exact historical derivation is uncertain, but the meaning is transparent from the kanji.