en_tn/exo/11/05.md

361 B

All the firstborn ... the firstborn of Pharaoh ... the firstborn of the slave girl ... the firstborn of the cattle

The "firstborn" always refers to the oldest male offspring.

who sits on his throne

This phrase refers to Pharaoh.

who is behind the handmill grinding it

"who is grinding at the handmill" or "who is behind the handmill grinding grain"