Like て, し is a 接続助詞（せつぞくじょし） (conjunction particle). This means that it is used for linking the (A) and (B) parts of a sentence, and describing that link in some way. The ‘description’ that し will highlight is ‘reasons’. Regularly it is translated simply as ‘and’.
し may be connected to the end of almost any word, but will require a だ before it when it comes after nouns or な-Adjectives. し will follow every ‘reason’ that is being listed in a sentence. However, the last し may be replaced with から or ので, before the ‘result’ is stated.

• 彼女（かのじょ）はピアノが弾（ひ）けるし、スポーツができるし、彼女（かのじょ）に出来（でき）ないことはないと思（おも）う。
  She can play the piano and she can do sports. I think there isn’t anything she can’t do.
• このレストランは高（たか）いし、まずいし、何（なに）もいいところがない。
  This restaurant is expensive and doesn’t taste good. There are no good parts.
• 彼（かれ）は真面目（まじめ）だし、親切（しんせつ）だし、彼（かれ）と友達（ともだち）でよかった。
  He is serious and nice. I am glad that he is my friend.
• 今日（きょう）は休（やす）みだし、晴（は）れだし、今日（きょう）は公園（こうえん）に行（い）こう。
  Today is my day off, and it’s sunny, so let’s go to the park.

Using し will indicate that each ‘reason’ being listed is of equal weight/importance. Because of this, it would not be appropriate to use in sentences where one of the reasons clearly far outweighs everything else.

• 昨日（きのう）は雨（あめ）が降（ふ）ってたし、おばあちゃんも亡（な）くなったし、悲（かな）しいな。
  It was raining yesterday and my grandmother also passed away, so I’m sad. (Unnatural Japanese, as the level of sadness between losing your grandmother, and it being a rainy day would be completely different)