Shy; timid or reserved in social situations—often used as a na-adjective.
彼はシャイで初対面の人と話すのが苦手だ。
He's shy and bad at talking to people he meets for the first time.
シャイな子どもは大勢の前で発表するのが怖いことが多い。
Shy children are often afraid to present in front of a large group.
面接ではシャイすぎる態度がかえってマイナスになることもある。
Being too shy in an interview can sometimes work against you.