i agree with toby. as an american, if you said that to me, i would think you’re a jerk. it’s just the way it’s phrased. if you want to tell someone that you simply want to explain it to them, you should probably phrase it differently, unless, of course, you’re trying to be rude. 😆 the non-rude way to say this could be: “it’s a metaphor, it’s really saying this...” OR “it’s a metaphor, it’s simply saying...” OR EVEN “it’s just a metaphor for...”

It depends on the context but it can sound a bit derogatory if you are speaking with a stranger or peers. only because it is implying that the person you are speaking with does not have the capability to understand it on their own. Not only that, but it is further implying that you would need to break it down into a unit as easy as spelling for them to be able to understand it. I feel like the phrase "let me spell it out for you" is usually only used in movies, in an argument, or in a passive aggressive statement. For example, if a guy repeatedly asked for a girl's number at a bar she may eventually say "Let me spell it out for you, im just not interested." Normally, i think the meaning of a metaphore would be explained as a questioning opinion or an opinion statement to be polite to your peers or a stranger. "I think this metaphore means _______, would you agree ?" "In my opinion, this metaphore means _______." Of course if you are a teacher or elder, you could get away with skipping the niceties, and just interject your ideas with little consequence. hope this helps.

Definitely not