Hast is an old way of saying “you have.” It belongs with thou, the old word for you when you spoke to one person: thou hast = you have. You will find it in older Bibles, in Shakespeare, and in old poems and hymns — Thou hast been our dwelling place. Nobody uses it in normal English today, except as a joke or to sound old on purpose. It is only that old “you” form. For he, she, and it, the matching old word was hath (today we say has). For I, it was already have. You may also see hast as a family name, but that is a different story; the meaning here is the old verb.

（古體）你有