en_tn_lite_do_not_use/exo/04/21.md

will harden his heart

Here "heart" refers to Pharaoh. His stubborn attitude is spoken of as if his heart was hard. AT: "will cause Pharaoh to be stubborn" (See: rc://en/ta/man/translate/figs-synecdoche and rc://en/ta/man/translate/figs-metaphor)

Israel is my son

The word "Israel" here represents all the people of Israel. AT: "The people of Israel are my own children" (See: rc://en/ta/man/translate/figs-metonymy)

is my son, my firstborn

Here the people of Israel are spoken of as if they were a firstborn son who causes joy and pride. AT: "is like my own firstborn son" (See: rc://en/ta/man/translate/figs-metaphor)

you have refused to let him go

The word "him" refers to the people of Israel as God's son. AT: "you have refused to let my son go" (See: rc://en/ta/man/translate/figs-metonymy)

I will certainly kill your son, your firstborn

The word "son" here refers to the actual son of Pharaoh.