one person / singleness, singularity / one's own efforts or strengths / an unmarried person, single

each person

one person

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

one day

What? What did you say?

one, 1 / the first in order, foremost / the beginning / the best / a kind of; one of something / (card games) an ace / unity / the bottom string of a shamisen or other Japanese musical instrument

Nothing

what / that thing (used in place of words you can't remember at the moment.)

the basics, a general idea