What is the meaning of 日?

short for 日曜日 (nichiyōbi): Sunday

陽: the sun

陽: sunlight, sunshine

陽: daytime, daylight

a day

time and date

a daily (something done every day)

the weather

a (usually unfortunate) case, event, situation

the times (age, era, or time in the past)

an auspicious or inauspicious aspect of a given day

a 家紋 (kamon, “family crest”) with a sun-shaped design

short for 日(일)本(본) (Ilbon, “Japan”)

the sun

sunlight, sunshine

daytime, daylight

a day

a reference to the imperial family or lineage, thought to be descended from the sun goddess Amaterasu

daytimes

number of days

days

Source: wiktionary.org