To hold or place something over (someone or something), e.g., holding an umbrella over someone to shield them.
彼は濡れないように自分の傘を差し掛けた。
He held his umbrella over her so she wouldn't get wet.
母は赤ん坊に毛布を差し掛けて眠らせた。
The mother covered the baby with a blanket and put him to sleep.
屋根の端に手を差し掛けてよじ登った。
He put his hand on the roof edge and climbed up.