konnichiwa (alternatively written konnichiha - see below) is a Japanese phrase meaning "Good Afternoon". It may be used any time from mid-morning (before which ohayou gozaimasu should be used) until the evening, when konbanwa is more appropriate.
konnichiwa follows the Japanese tradition of roundabout speech, and literally means "As far as today is concerned..."
The characters making up konnichiwa are as follows:
Pronunciation is quite straightforward, but it should be noted that the two 'n' sounds are distinct, with the first being a nasal, and the second a normal 'n'. Two syllable sounds should be spoken.