"The young man was born in New York."
Translation:Iuvenis Novi Eboraci natus est.
JefDeSmedt is correct. It is a difference between singular and plural respectively
different case: "-i" ending here is locative, meaning translated as "in New York" (can also be genitive, possessive translated as "of New York"); "-um" ending is nominative (subject), accusative (object), or vocative (speaking to New York). In Latin, there is no sentence order, but nouns are declined with different endings to distinguish the case they are in within the sentence