前者/後者

The words 前者 and 後者 mean the Japanese equivalent of the "former" and "latter", respectively. They're used to separately refer to two things that were previously mentioned in a sentence.

日本のお城と言えば、姫路城や大阪城が有名だ。前者は兵庫県にあって、後者は大阪府にある。
Speaking of Japanese castles, Himeji Castle and Osaka Castle are famous. The former is in Hyogo Prefecture, and the latter is in Osaka Prefecture.

今日はクラスで、アメリカでフロリダ州とカリフォルニア州について学んだ。前者はとても保守的で、後者は保守的じゃないんだよ。
Today in class, we learned about the states of Florida and California in the US. The former is very conservative, and the latter is not.

手塚治虫が描いたマンガでは「ジャングル大帝」や「ブラックジャック」が人気がある。前者は白いライオンの話で、後者はどんな病気でも治すことが出来る医者の話だ。
The manga "Great Emperor of the Jungle" and "Black Jack" by Osamu Tezuka are popular. The former is a story about a white lion, and the latter is about a doctor who can cure any kind of sickness no matter what it is.

日本の代表的な伝統芸能に能と狂言がある。前者は悲劇で後者は喜劇だ。
Noh plays and kyogen are representative of Japanese traditional arts. The former is a tragedy, and the latter is a comedy.