Usually, the clients appreciate his readiness to use their language and this has often been a significant factor in closing a deal.

readiness 是形容词 ready（准备好的、愿意的）加上名词后缀 -ness 构成的名词，表示"准备好的状态"或"愿意的态度"。 在这个句子中，readiness 特指"愿意使用客户语言的态度"，这种积极态度有助于建立信任、促进交易。