give (someone or something) a hand
1. To help someone with something. I hope that someone will give me a hand with these bags—there's no way I'll make it to the fifth floor on my own! No, Billy can't babysit, he's giving me a hand with my car today.
2. To applaud someone or something. Wasn't that a great performance? Let's give them a hand, ladies and gentlemen!
give a hand
1. Also, lend a hand. Help a person, as in Let me give you a hand with those chairs, or Jane is always willing to lend a hand with refreshments. [Mid-1800s]
2. Also, give a big hand. Give an enthusiastic round of applause, as in Please give her a hand. One can also be given applause or get a big hand, as in This speaker always gets a big hand. [Early 1800s]
give (or lend) a hand
assist in an action or enterprise.