const rules = new Intl.PluralRules("ar");
console.log([0, 1, 2, 5, 11, 100].map((n) => rules.select(n)).join(" "));
zero one two few many otherArabic uses all six CLDR plural categories. 0 is zero, 1 is one, 2 is two, 3 to 10 are few, 11 to 99 are many, and 100 is other. So a translation of "N messages" into Arabic needs six versions of the sentence.
"other one other other other other" is the tempting wrong answer. That is the English pattern (one for 1, other for the rest), and it is exactly what a count === 1 check produces.