Oliver Cowdery initially wrote my word in 𝓟, then almost immediately corrected the phrase to my words (the level of ink flow is unchanged). His correction apparently followed the reading of the original manuscript (which is no longer extant here). This plural use of words both precedes and follows in this passage: “the words of your seed” and “my words shall hiss forth”.
There is one other occurrence of “word(s) hissing forth”, and this one has the singular word rather than the plural words:
Despite this difference, the occurrence here in 2 Nephi 29:2 is clearly plural because of the consistency of the plural in the whole passage. More generally, God’s word can be referred to in either the singular or the plural. For some statistics regarding “my word(s)”, see under 1 Nephi 16:24.
Summary: Retain in 2 Nephi 29:2 the plural words, which is consistent for this passage and most probably represents the reading of the original manuscript.