King Mosiah had translated the plates “by the means of those two stones which were fastened into the two rims of a bow” (Mosiah 28:13). In verse 23, Alma declares that there was a stone, “which shall shine forth in darkness unto light,” that could be used to discover the secret works of the Jaredites. In other words, the stone could be used to translate and interpret the plates.
Lest we become confused with the singular word stone, verse 24 clarifies that this named instrument, Gazelem, was “these interpreters [which] were prepared that the word of God might be fulfilled.” These interpreters accompanied the plates from the time they were hidden, so that they might be understood (see Ether 4:5).