Something that's tuneful or pretty to listen to is melodic. If your French teacher has a friendly smile and a melodic voice, you could probably sit and listen to her talk for hours.
Anything sweet sounding — a bird's trill, a poet's voice, or the tune you sing in the shower — is melodic. A more technical meaning of the word is "containing melody," the definition a professional musician might use. Melody is a quality of music defined as "tunefulness" or "a satisfying series of notes." Music teachers play melodic patterns for their students to duplicate, and composers sometimes combine melodic phrases to form a symphony. The Greek root of melodic is melos, or "song."