Pandan comes from extracting the leaves of the Pandan plant and its flavor is somewhat like a mixture of vanilla and coconut. Mochi is typically an Asian sweet made with glutinous rice flour with a springy, chewy texture.
Traditionally coconut mochi lies more along the Vietnamese spectrum of sweets and usually doesn't include the pandan. Feel free to omit it if you wish though I personally think the pandan brings out the flavor of the coconut as well :)
