La ilaha illa anta subhanaka inni kuntu minaz zalimin means "there is no god but You, glory be to You, I have been one of the wrongdoers". Prophet Yunus said it in the belly of the whale, and Allah saved him.
لَآ إِلَٰهَ إِلَّآ أَنتَ سُبْحَٰنَكَ إِنِّى كُنتُ مِنَ ٱلظَّٰلِمِينَ
Lā ilāha illā anta subḥānaka innī kuntu minaẓ-ẓālimīn
There is no deity except You; exalted are You. Indeed, I have been of the wrongdoers.
Quran 21:87, Sahih International
وَذَا ٱلنُّونِ إِذ ذَّهَبَ مُغَٰضِبًۭا فَظَنَّ أَن لَّن نَّقْدِرَ عَلَيْهِ فَنَادَىٰ فِى ٱلظُّلُمَٰتِ أَن لَّآ إِلَٰهَ إِلَّآ أَنتَ سُبْحَٰنَكَ إِنِّى كُنتُ مِنَ ٱلظَّٰلِمِينَ فَٱسْتَجَبْنَا لَهُۥ وَنَجَّيْنَٰهُ مِنَ ٱلْغَمِّ ۚ وَكَذَٰلِكَ نُۨجِى ٱلْمُؤْمِنِينَ
Wa Zan Nooni iz zahaba mughaadiban fazaanna al lan naqdira 'alaihi fanaadaa fiz zulumaati al laaa ilaaha illaaa Anta Subhaanaka innee kuntu minaz zaalimeen Fastajabnaa lahoo wa najjainaahu minal ghamm; wa kazaalika nunjil mu'mineen
And [mention] the man of the fish, when he went off in anger and thought that We would not decree [anything] upon him. And he called out within the darknesses, "There is no deity except You; exalted are You. Indeed, I have been of the wrongdoers." So We responded to him and saved him from the distress. And thus do We save the believers.
Quran 21:87-88, Sahih International translation
Our teachers will check the Arabic and transliteration on this page before launch.
Guide
La ilaha illa anta subhanaka inni kuntu minaz zalimin means "there is no god but You, glory be to You, indeed I have been one of the wrongdoers". It is the dua of Prophet Yunus (Jonah), known as Dhun-Nun, "the man of the fish".
Yunus left his people in anger before Allah gave him leave. He boarded a ship, was cast into the sea and swallowed by a great fish. In the layers of darkness, of the night, the sea and the fish, he called out with these words. Allah says: "So We responded to him and saved him from the distress. And thus do We save the believers" (Quran 21:87-88). The last words, "and thus do We save the believers", show the promise is for us too.
The Prophet ﷺ said: "The dua of Dhun-Nun when he called upon Him in the belly of the fish was: la ilaha illa anta subhanaka inni kuntu minaz-zalimin. No Muslim ever calls upon his Lord with it for anything, except that He answers him" (Jami at-Tirmidhi 3505, graded sahih by al-Hakim and al-Albani).
In distress, anxiety or grief, after a sin, and before asking Allah for something you need. Some people recite it in large numbers together in a gathering. There is no fixed number for that in the hadith, so it is better to say it sincerely, on your own, as often as you like.
La ilaha illa anta subhanaka inni kuntu minaz zalimin, lailaha illa anta subhanaka inni kuntu minaz zalimeen and la ilaha illa anta subhanaka inni kuntu minadh-dhalimin are the same words. The z in zalimin is the Arabic ظ, a heavy "th".
Questions
There is no god but You, glory be to You, indeed I have been one of the wrongdoers.
Prophet Yunus (Jonah), in the belly of the fish (Quran 21:87).
In distress, anxiety or grief, after a sin, and before asking Allah for what you need. The Prophet ﷺ said no Muslim calls with it except that Allah answers him (Tirmidhi 3505).
No number is fixed in the hadith. Say it sincerely, as often as you like.