The 1830 typesetter added the -eth ending to the verb, probably because he interpreted the initial what as the subject of the clause, when in actual fact “these things” is the subject. Note, for instance, that in standard English we have “what do these things mean”, not “what does these things mean”. Since “these things” is plural, the reading of the manuscripts is correct, even though the original text allows -(e)th to occur with plural subjects, as in Mosiah 12:20 (“what meaneth the words which are written”) and Helaman 5:38 (“what doth all these things mean”). But here in 1 Nephi 22:1, the earliest text supports the standard plural form mean. For further discussion, see infl al endings in volume 3.
Summary: Restore the original reading “what mean these things” in 1 Nephi 22:1, which is grammatically correct for Early Modern English.