en_tn/isa/48/12.md

General Information:

Yahweh continues speaking to the people of Israel.

Jacob, and Israel

Both of these refer to the people of Israel. (See: rc://en/ta/man/jit/figs-doublet and rc://en/ta/man/jit/figs-metonymy)

I am the first, I also am the last

This phrase emphasizes Yahweh's eternal nature. Possible meanings are 1) "I am the one who began all things, and I am the one who ends all things" or 2) "I am the one who has always lived, and I am the one who always will live." See how you translated a similar phrase in Isaiah 44:6. (See: rc://en/ta/man/jit/figs-merism)