When someone dies, we say “inna lillahi wa inna ilayhi rajioon.” It means, roughly translated, “We belong to Allah and to Him we return.”
Inshallah here, we’ll do a brief (grammatical) dissection of the phrase, so you can understand the words better (and not mix them up / mispronounce them). If you hover your mouse over underlined words, you’ll see the Arabic inshallah.
Inna: Inna is really inna-na. The first part is “very”, the last part is “we”–but Arabs like to simplify, so they just write it as inna (with only two noons). It means “Indeed, we” or “verily, we”.
Li-llahi: Li is a harfu jarr (preposition) meaning “to” or “is for.” We use it as a kind of possessive case. “a laka akhun” (the la is really the same as li) means “is for you a brother?” or “do you have a brother?” So here, “lillahi” means “belong to Allah” or “are for Allah”. (It’s also because of the li that Allah takes kasra.)
Wa: Wa means “and”.
Ilay-hi: This is two parts, it means “to him”. Ilay is actually a form of ila (a preposition), which means “to”. We say things like, “thahabtu ila masjidin” — I went to a masjid. “Hi” is actually “hu“, the third-person possessive pronoun (“his”). (It takes kasra because of ila.) So the overall translation is “to him”.
Rajioon: This is some form of the verb “to return”, not sure on the details–people usually translate it as “we will return.” It is plural (so refers to 3+ people).
So taken together, we get a translation of “indeed we belong to Allah, and indeed to him we return.”