They’re all different words.
Ze/zij = she (singular) or they (plural). For ze it depends on the other words in the sentence which it is, “ze eet soep” uses singular verb, thus it is she, “ze eten soep” uses plural verb, so it is they.
Je/jij = you (singular), jullie = you (plural), English doesn’t seperate the two words, but Dutch does. Similar to Dutch ze, the way to see which to use in the Dutch translation, is looking at the verb.