〜し
…and…, what's more — listing reasonsmachine translation
FormationPlain form + し (nouns and な-adjectives + だし)
し joins plain-form clauses to LIST reasons or qualities, with the implication "and more besides, not just this": 安いし、おいしいし、よく来ます (it's cheap, and it's tasty, so I come often). Nouns and な-adjectives add だ: 雨だし、寒いし.
Compared with the て-form linking you learned at N5 (安くておいしい), し emphasizes that each clause is A REASON. Often the concluding clause is left unsaid, and the listener fills it in: 今日は雨だし… (it's raining today, on top of everything, so…).
A single し is enough when you give one representative reason and imply there are others: 時間もないし、今日はやめましょう. The particle も often accompanies the し clauses to heighten the feeling of reasons piling up.
Examples
この店は安いし、おいしいし、よく来ます。
This place is cheap and the food is good, so I come often.
今日は雨だし、寒いし、家にいましょう。
It's rainy and cold today — let's stay home.
彼は親切だし、日本語も上手だし、みんなに人気があります。
He's kind, and his Japanese is excellent, so everyone likes him.