en_tn_condensed/isa/57/15.md

For this is what the high and elevated One says

The words "high" and "elevated" have basically the same meaning here and emphasize Yahweh being exalted. See how you translated this in Isaiah 6:1 and Isaiah 33:10. See how you translated a similar phrase in Isaiah 52:13.

to revive the spirit of the humble ones, and to revive the heart of the contrite ones

These two phrases mean basically the same thing and emphasize that Yahweh will strengthen and encourage those who humble themselves before him. (See: rc://en/ta/man/jit/figs-parallelism)

spirit ... heart

Here these refer to a person's thoughts and emotions, not the spirit and heart literally. (See: rc://en/ta/man/jit/figs-metonymy)