(cliché)  Fig.: to offer and give protection to someone. Also to guide someone.

The foreman took the young workers under his wing and they learned the job in no time

Il caporeparto ha preso sotto le sue ali gli ultimi arrivati che hanno così imparato in men che non si dica

That's incredible! Our old dog found three abandoned kittens and took them under his wing, protecting them from anything and anyone

Incredibile! Il nostro vecchio cane ha trovato tre gattini abbandonati, li ha presi sotto le sue ali e li protegge da tutto e da tutti

The school bully stopped harassing the new student when big Peter took him under his wing

Il bullo della scuola ha smesso di infastidire il nuovo studente quando Pietro-il-forte l'ha preso sotto le sue ali

It's easy to see how this expression refers to mother hens, as well as to the other female birds, sheltering their chicks under their wings