to boil water

to use / to employ / to make use of, to apply / to spend

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

a kettle (vessel for boiling a liquid or cooking food) / Clipping of 薬缶頭 (“bald head”).

bald head

(idiomatic) to lose one's temper, to fly off the handle

to use one's head

use one thing for many purposes / work someone hard