they are old fashioned ways of saying 'you' and 'your'

In old-fashioned English, "thee," "thou," and "thy" were used for the second person singular familiar form. In modern English, they have been lost and "you" and "your" are used for everything. In a famous 1611 English translation of the Bible, the King James version, Psalm 23 contains the words "I will fear no evil: for thou art with me; thy rod and thy staff, they comfort me." ("porque tú estarás conmigo. Tu vara y tu cayado me infundirán aliento.") In a modern translation: "I will fear no evil, for you are with me; your rod and your staff, they comfort me." Because we no longer have a distinction between the familiar and formal forms of address, familiarity and formality are indicated in other ways. My friends call me "Dan," in very formal circumstances I'm called "Mr. Smith," but either way I am called "you." In the 1600s, family and close friends would have addressed me as "thou" or "thee" rather than "you."

Some Spanish dictionaries include these words. Gran Diccionario Oxford thee | AmE ði, BrE ðiː | pronoun (archaic) te; (after prepositions) ti thy | AmE ðaɪ, BrE ðʌɪ | adjective (archaic) tu ▸ Thy will be done hágase tu voluntad thou | AmE ðaʊ, BrE ðaʊ | pronoun (archaic or literary) tú; (Religion) vos (archaic)

You need a standard dictionary, not a student dictionary of common words and not a pocket dictionary of common words. New Oxford American Dictionary thy | ðaɪ | (also thine before a vowel) possessive determiner archaic or dialect form of your: honor thy father and thy mother. thee | ði | pronoun [second person singular] archaic or dialect form of you, as the singular object of a verb or preposition: we beseech thee O lord. Compare with thou1. thou | ðaʊ | pronoun [second person singular] archaic or dialect form of you, as the singular subject of a verb: thou art fair, O my beloved. Compare with thee.