a helping hand; a little help; some assistance
Formal or literary term for a small amount of help or assistance. Often used in expressions like 一臂の力を貸す (to lend a hand).
He lent me a helping hand.
Could you give us a little help with this project?
From 一 (one) and 臂 (arm), literally 'one arm', used figuratively to mean a small amount of help.