"When you give someone your business card you must hold it lower than theirs."
"Business cards must be handed over from below."
"business cards" 「名刺」
"must be handed over" 「渡さなければならない」
"to hand over" 「渡す」"to give/be given" や "to pass/be passed" も言えます。
"from below" 「下から」
"When you give someone your business card you must hold it lower than theirs."
"When you give someone your business card" 「名刺を渡すときに」
"you must hold it lower than theirs" 「相手のより下持たなければならない」
[渡す](https://eikaiwa.dmm.com/uknow/questions/32805/)についてもっと詳しく知りたい方はクリックしてください。
It's a custom for Japanese people to hand their business card to others lower than the person they are giving their card to.
この場合、次のような言い方ができます。
ーIt's a custom for Japanese people to hand their business card to others lower than the person they are giving their card to.
「日本人は名刺を渡す相手より下から名刺を渡すのが慣習です」
to hand one's business card で「名刺を渡す」
lower than the person they are giving their card to で「彼らが名刺を渡す相手よりもっと低く」
ご参考まで！
オーストラリア 
カナダ 
