This is the 1933rd most frequent Turkish word.
kişiyle
"With the person" or "with a person."
'Kişiyle' means 'with a person' in this context, indicating he had a conversation involving someone.
O yemek için bir kişiyle konuştu.
He talked with a person for the meal.
Here, 'kişiyle' conveys the meaning of sharing the same car with a person.
Bir kişiyle aynı arabaya bindik.
We got into the same car with a person.
In this sentence, 'kişiyle' implies performing the action of swimming together with someone.