For me it’s gotta be “Morte e Vida Severina”/ “Severino Death and Life”. It’s an epic poem narrating the journey of a poor man from Northeastern Brazil, a famously poor and segregated region that’s frequently affected by severe droughts, fleeing from his home and walking to the big city to survive the season. On the way he describes all the misery he experiences and sees.
One stanza that has stuck with me for years goes something like this "And all of us Severinos/With the same lives/Will die of the same/Severe Severino death,/The death died of/Old age before thirty/Of an ambush before twenty/And of hunger day by day/(Of weakness and plague/The Severino death/attacks at all ages/even those not born)
“The Phantom Tollbooth” by Norton Juster. Ok, I’m flipping the question because I’m a native English speaker, but for all the readers filling this thread with great recommendations from other countries, I suggest you pick up The Phantom Tollbooth, if you haven’t already.
Wikipedia tells me that the book has been translated into many languages, but I can’t imagine how that was done, and I doubt it recaptured the magic. The book is an Alice in Wonderland like magical story about the adventures of a little boy in an imaginary land built from wordplay, puns, and interpreting English idioms very literally.