But what would the ciphertext be, or the output?

但是密文是什么，或者输出是什么？

For example, E is the most common letter in English, so if your cipher translates E to an X, then X will show up the most frequently in the ciphertext.

例如，E 是英语中最常见的字母，因此如果您的密码将 E 翻译成 X，那么 X 将在密文中出现得最频繁​​。

In order to make information secret, you use a cipher – an algorithm that converts plain text into ciphertext, which is gibberish unless you have a key that lets you undo the cipher.

为了使信息保密，您使用密码——一种将纯文本转换为密文的算法，除非您有可以解开密码的密钥，否则这是乱码。