to lend a hand, to give a little push
Você pode me dar uma forcinha com essa mudança? São poucas caixas.
Can you lend me a hand with this move? It's just a few boxes.
The expression builds transparently on força ("strength"): dar uma força literally means "to give a strength", that is, to lend someone your effort or support.
Falando's Idiom Trainer teaches you to recognize idiom meanings and create sentences using them, so you can speak like a Brazilian.