What does the saying " let them eat cake mean" if anyone knows it would be very helpful, thank you

Marie Antoinette is supposed to have said this when she was told that the peasantry had no bread to eat. There's no evidence to support this story though.
At one time it the higher class of royalty were buried with cake when they died so they would have something good to eat. I don't know what this was in reference to but now there is a saying "Don't that Take the Cake" usually meaning that is was not the best thing that could happen.

Could mean to let someone relax or take it easy... But I have not really heard this used as a figure of speech, what you may be referring to is: To wish to "have one's cake and eat it too" is an idiomatic phases and a figue of speech in the English language. It means to have success and enjoy it at the same time.
Or there is "you can't have you cake and eat it too" which means one wants more than one can handle o deserve, or the desire to have 2 different things that one cannot possibly have together.
Some examples: 1) A man who loves to take photographs owns his own photography studio. He loves his work and makes great money... One could say, " he has his cake and eats it too".
2) A man works so hard to pay for a fancy house that he never has any time to stay home and enjoy... One could say that "he can't have his cake and eat it too"
3) A little girl asked her parents to buy her a pet pink kitten, but live kittens do not come in the color pink, so she could choose to have a pink stuffed animal kitten or a live kitten in a natural color. She chose the live kitten in a natual color because having a real pink kitten could neve be an option. She could say, "I can't have my cake and eat it too"
I hope this helps...
Is there a cetain phase using these words that you need or would like to know or understand?

Falsely (most likely) attributed to marie antoinette... a young queen with no concept of the common person...

You ask what its meaning is... generally its taken to show the arrogance or ignorance of the aristocracy... you would take it as ignorance if she didn't understand when told the poor had no bread that they would also have no cake to eat... or arogance if she meant it sarcastically... though some debate the meaning of "cake" in her time.

In a completely stupid analogy, itd be like saying the poor cannot afford a CD player and you said then let them use an iPod. Sort of. Not really. I mean not affording bread is about starvation. Not affording a musical device is about boredom... but hey, I said it's a stupid analogy fom the start. OK.. how about they cannot afford broccoli so let them eat asparagus? There. That's my quote of the day. I give up.

But again, there's enough controvesy about whether she really said it, or said it fist.

Sorry, I misread the question the first time...
Marie Antoinette is supposed to have said this when she was told that the peasantry had no bread to eat. There's no evidence to support this story though, and a lot of controversy surrounds this phrases true meaning.
Today in the English language, the phrase "let them eat cake" illustrate the divide between rich and the poor.
In the original French writings of this phrase "cake" is a mistranslation, "Qu'ils mangent de la brioche (an expensive egg based bun)", It's not quite cake, but still a more delightful food than plain bread.
Because of this, some argue that "Qu'ils mangent de la brioche" isn't quite as cold a sentiment as you might think. At the time, French law required bakers to sell fancy breads at the same low price as the plain breads if they sold out. The goal was to prevent bakers from making very little cheap bread and then profiting off the fancy, expensive bread. Whoever really said "Let them eat brioche" may have meant that the bakery laws should be enforced so the poor could eat the fancy bread if there wasn't enough plain bread to go around.
But no one really know...

I heard it said that cake was a European term regarding soot deposits in the fireplace. Bricks and layers of ash and soot build and collects in the fireplace flu and eventually breaks and falls off. At the time of the revolution, people had no flour for bread, especially when it was rumoured to be stockpiled at the king and queen's palace. This eventually lead to the beginning of the revolution. Most people had fireplaces but no flour at that time to make bread. That was her way of off-handedly saying, "it's their problem, not mine."
It wouldn't make sense to tell them to eat cake, which was more expensive than bread... just a thought.