其实，You have my word 的意思很简单，就是“我保证，我承诺”，word在这里是不可数名词，表示“承诺”，这句话语气比较重，偏口语化。
A: "I'm leaving the kids with you. Promise me you'll keep them safe while I'm gone."
A：“我把孩子留给你照看了，在我离开期间你一定要保护好他们的安全。”
B: "You have my word."
B：“我保证。”
那么，除了you have my word之外，这里还有一些同义表达，也都可以表示“我保证”，而且都非常地道。
I give you my word.
这句话中的word也同样指的是“保证，承诺”，所以I give you my word的意思就是“我向你保证，我向你承诺”。
I give you my word that this won't happen again.
我向你保证这种事不会再次发生。
I give you my word that I will keep our secret.
我向你承诺不会泄露我们之间的秘密。
I swear to you/God.
大家都知道，swear的意思是“发誓，起誓”，所以I swear to you/God这句话的语气比起You have my word更为强烈，已经用个人人格作担保来表明对某事/某人的态度，即“我向你发誓，我以神明起誓”...
I swear to you that I'm not lying.
我对你们发誓，我没有撒谎。
I swear to God I had nothing to do with that car accident.
我以神明起誓，那场车祸跟我一点关系也没有。
关于word，其实在英文中还有许多地道实用的相关表达，一起来学习一下吧。
a man/woman of his/her word
短语 “a man of his word” 或 “a woman of her word” 的意思是 “一个言之有信、说话算数的人”。它形容人诚实可靠、值得信赖，答应的事情一定能办到。
Terry is very reliable. You can always trust something will get done well when he says he'll do it. He's a man of his word.
泰瑞很可靠。当他承诺说会做一件事情的时候，你就大可放心，这件事肯定能办好。他是个言而有信的人。
Our neighbour said he was a man of his word but we realised he wasn't. He told us he would return the things he had borrowed from us but he still hasn’t!
表达 word of mouth 直译过来是“嘴里说出的话”，指人与人之间传播信息时的口头传述方式，和文字传播是一组对立概念。
该说法的形容词形式是加连字符的“word-of-mouth 口碑的，口口相传的”，多用于谈论广告、宣传和营销的商业语境中。人们在这个表达前常使用介词 by，意思是消息通过口头转述的方式 by word of mouth 传播开来。.
These days, food rating apps are becoming very popular. This is why many restaurants have started to put a high value on online word-of-mouth marketing.
如今，美食评论应用正广泛地普及开来。这就是为什么很多餐厅开始非常重视网络口碑的营销策略。
Folk tales are passed on by word of mouth, leaving no written records of who the authors might be.
