Question about Japanese Kanji?

1. kanji - represent meanings, not pronunciations.

日 - can mean day, sun etc. It has multiple pronunciations: hi, nichi, ka etc.

By itself, usually "hi".

Sunday: 日曜日 - nichiyoubi (first kanji is nichi; last is "hi" but changes to "bi" because of the Y of "you".).

1日 - the first day of the month: tsuitachi

2日 - the second day of the month: futsuka

今日 - today: kyou

It's more complicated than you imagine. In some cases, like tsuitachi and kyou, the kanji combine to create a new pronunciation distinct from the normal readings of the individual kanji.

hi, ka -- are native Japanese readings for 日. nichi - is Sino-Japanese (originally from a Chinese language, often adopted 1000 years ago or more).

2. kana - represent pronunciations, specifically mora (the Japanese idea of a syllable, not quite the same as ours), and not meanings. Theoretically, any Japanese word can be written in kana. They do not have meaning by themselves. Context is required.

3. kanji - are used for nouns, many pronouns, adjectives, adverbs, and the roots verbs and verbal adjectives. They are often simpler than writing the pronunciations in kana (but not always).

4. hiragana, is used for the grammatical glue of Japanese, such as particles (aka postpositions), prefixes, suffixes, and other inflectional changes. Also used for any words without kanji. (Only about 2000 Chinese symbols are used by the Japanese. Many characters are not used, and none of them were designed for Japanese, so sometimes there simply is no equivalent Chinese character for a native Japanese word).

5. katakana -- used for foreign words of Western origin (allows for syllables native monolingual Japanese can pronounce but which are not allowed in native Japanese words); also for onomatopoeia, scientific names of animals, plants, minerals etc; the names of many Japanese companies, and a use similar to italics (for emphasis).

6. Somewhat like in English:

hi -- has no meaning without context.

Hi! (hello). hit. (need the T to understand its pronunciation). high (the gh change meaning).

Kanji are somewhat like numerals. 1, 2, 3. Have different pronunciations depending on the language that uses them, but the same meaning.

But I can write their pronunciations using a phonetic system, like the Latin alphabet:

one, two, three (English); un, deux, trois (French); eins, zwei, drei (German); uno, duo, tre (Italian); ichi, ni, san (Sino-Japanese numbers); hito-, futa-, mi- (native Japanese numbers, that can't stand alone).

Note: Japanese does use the same numerals (Hindu-Arabic numerals, that are not kanji but are ideograms like kanji), but it also has true kanji (adopted from Chinese characters, a different ideographic system) to represent numbers as well.