You have to accustom your ears and your mouth to sense the difference. therefore, I suggest you go to Google/Translate, type "un pain, une pomme" on the French side, then click on the small loudspeaker, listen, repeat, listen, repeat, listen, repeat...... again, again, until you hear the difference and pronounce it correctly (hearing your own voice).
"une personne" is "a person". In French, it happens that it is always used in singular, even if the person is a man.
Tenses are involved with verbs, to position the action in time: present, past, future, etc.
There is no link between the gender of a subject noun and the tense of the verb.