My candle burns at both ends.
This is an idiom that refers to overextending oneself. When a person burns the candle at both ends, they are doing too much of something (perhaps working or partying) without sufficiently resting. While a candle lit at just one end will run its natural course, a candle burning at both ends will give off more light and quickly burn out. This represents the speaker's passionate and intense lifestyle.
But ah, my foes, and oh, my friends—
This line uses alliteration and repetition to place the speaker's friends and enemies in the same camp. The "m" and "f" sounds repeat successively with the words "my foes" and "my friends." The fact that the speaker has enemies as well as friends shows that she lives intensely, authentically, and perhaps controversially. However, she addresses both her friends and her enemies in this poem without distinguishing a preference for one or the other.
It gives a lovely light!
In the final line of the poem, the speaker exclaims how lovely her light is. This line could be interpreted as having a self-mocking tone, but overall, the speaker celebrates her short-lived and passionate life.
