Questions & Answers about Сто людей у парку.
Because after сто (one hundred), Ukrainian uses the genitive plural form of the noun.
- люди = people (basic dictionary/plural form)
- людей = of people / people after many numerals
So:
- сто людей = one hundred people
- not сто люди
This is a very common pattern with larger numbers in Ukrainian.
The basic form is люди (people).
людей is a different case form of the same noun. The noun людина means person, and its plural is люди. Its genitive plural form is людей.
So the forms are:
- singular: людина = person
- plural: люди = people
- genitive plural: людей