"Big hand" is an Engpsh idiom used to express applause or cheers for someone. It is derived from the physical gesture of clapping one's hands together, with the "big" referring to the loudness or intensity of the applause.
Here are some examples of how "big hand" can be used in a sentence:
"Let's give a big hand to the graduating class of 2022!" (给2022届毕业生鼓掌！)
"The crowd gave a big hand to the winning team." (人群为获胜队伍鼓掌)
"After the singer's last song, the audience gave her a big hand."(歌手最后一首歌演唱完后，观众给了她热烈的掌声)