はもちろん, or occasionally は勿論（もちろん）, is a phrase in Japanese that presents (A) as being something obvious, while (B) should still be considered/mentioned. In this expression, the 副助詞（ふくじょし） (adverbial particle) は presents (A) as being a stand-alone topic, before the 副詞（ふくし） (adverb) もちろん ‘naturally’ emphasizes that (A) is what it is. After this, the (B) part of the sentence will describe some other factor that is worth mentioning.
はもちろん will be used directly after noun (A), before the sentence will go on to discuss noun (B). This construction can be translated as ‘not only (A), but (B)’, ‘not to mention (A), (B)’, and other similar English expressions.

• パソコンのことはもちろん、電化（でんか）製品（せいひん）の事（こと）ならなんでも聞（き）いてください。
  Please ask me anything, not only about computers but also other electronics.
• 数学（すうじ）はもちろん、学校（がっこう）の科目（かもく）を全（すべて）て一人（ひとり）で教（おし）えることができる人（ひと）を探（さが）している。
  We are looking for someone not only who can teach math, but every subject in this school by themselves.

In many cases, despite (A) being the obvious factor, (B) is being highlighted as sharing similar　qualities to (A). This means that in はもちろん sentences, も will almost always be seen after (B).

• 彼女（かのじょ）は日本語（にほんご）はもちろん、韓国（かんこく）語（ご）も話（はな）すことができます。
  Not only can she speak Japanese, but she can also speak Korean.
• この作家（さっか）の本（ほん）はもちろん、歌（うた）もうまいから人気（にんき）がある。
  This author is popular, not only because of his book, but also because he is a good singer.