Meaning of these oscar wilde lines?

In those lines, the poem is describing an imaginary realm of spiritual and artistic perfection. To say that a "pipe is ever dropping honey" is a metaphorical way of saying that beautiful music is always playing. (In this context, a "pipe" is a musical instrument.) A lyre is another musical instrument. To say that its strings are "ever strung" probably means that it's always perfectly in tune, always ready to be played.