module ActionView::Helpers::TextHelper

# => 2 Personen
pluralize(2, 'Person', locale: :de)

# => 0 people
pluralize(0, 'person')

# => 3 users
pluralize(3, 'person', plural: 'users')

# => 2 people
pluralize(2, 'person')

# => 1 person
pluralize(1, 'person')

See ActiveSupport::Inflector.pluralize
(you must define your own inflection rules for languages other than English).
The word will be pluralized using rules defined for the locale

which defaults to I18n.locale
it will use the Inflector to determine the plural form for the given locale,
+plural+ is supplied, it will use that when count is > 1, otherwise
Attempts to pluralize the +singular+ word unless +count+ is 1. If

def pluralize(count, singular, plural_arg = nil, plural: plural_arg, locale: I18n.locale)
  word = if count == 1 || count.to_s.match?(/^1(\.0+)?$/)
    singular
  else
    plural || singular.pluralize(locale)
  end
  "#{count || 0} #{word}"
end