learn hiragana. Japanese kana, kanji etc.

Kanji are from the beginning Chinese characters imported to Japan In the 3rd and 4th centuries AD by immigrating Chinese and Koreans. The Japanese language at that time existed in spoken form only, so during nearly 400 years the Chinese characters was incorporated in to the Japanese language.

To make it a little bit more complicated, a Kanji can have many different pronunciations.

Kun-yomi: Written Chinese characters were used to express Japanese spoken words of like meaning. When a Japanese word's sound is expressed by a Kanji, the reading, or pronunciation of that character, is called a Kun-yomi reading, and is usually followed by a Japanese inflectional stem written in Hiragana, known as Okurigana.

On-yomi: For Chinese characters where there were no Japanese meaning or where the character had different meaning the Chinese pronunciation was used. Single Kanji usually have Kun-yomi readings, and Kanji in compounds usually have On-yomi readings. Most modern Kanji have about 2 - 3 Kun-yomi and 2 - 3 On-yomi readings each today!

This is the Chinese character for "sky, heaven". In Chinese it is pronounced "tian"
On-reading: would in Japanese be: Ten
Kun-readings: Ame

This is the Chinese character for "mountain". In Chinese it is pronounced "shan"
On-reading: would in Japanese be: San
Kun-readings: Yama