Meaning of xià shǒu:
下手
to start; to put one's hand to; to set about
Wǒ bù zhīdào cóng nǎlǐ xiàshǒu.
我不知道从哪里下手。
I don't know where to start.
Tā zhǔnbèi kāishǐ xià shǒu gōngzuò.
他准备开始下手工作。
He is ready to start working.
Tā juédìng mǎshàng xiàshǒu kāishǐ xiūlǐ zhè liàng jiùchē.
他决定马上下手开始修理这辆旧车。
He decided to set about repairing the old car immediately.
the seat to the right of the main guest
Tā zǒngshì zuò zài zhǔ bīn de xià shǒu wèizhì.
他总是坐在主宾的下手位置。
He always sits in the seat to the right of the main guest.