Here's how it works:
* First person: "I walk"
* Second person: "You walkest" (archaic) or "You walk" (modern)
* Third person: "He/She/It walks"
Note: While the "-est" form was common in older English, it's no longer used in modern English. The modern second person singular form is the same as the plural: "you walk".
So, while "-est" was historically used for the second person, it's not a standard form in modern English.