particle, conjunction
and; besides; moreover; not only ... but also
Lists parallel reasons or facts, often with an additive or emphatic nuance. Used after the plain form of verbs, adjectives, and nouns.
この店は安いし、美味しいし、よく来ます。
This restaurant is cheap, and the food is good, so I come here often.
彼は優しいし、面白いし、人気がある。
He is kind, and funny, so he is popular.
particle, conjunction
Gives one reason among others, often implying there are additional unstated reasons. Usually indicates one of several reasons.
雨も降ってきたし、今日は出かけるのをやめよう。
It's started raining, and (for that and other reasons) let's not go out today.
particle, conjunction
the thing is; for one thing
Used at the end of a sentence to give a reason for an unstated but deducible conclusion. Often softens a statement or implies 'you know'.
だって、私も忙しいし。
Well, I'm busy too, you know.
もう遅いし、帰ろう。
It's late, so let's go home (implying that's a good enough reason).