I think what they're trying to say here is that cardinal numbers do not change* in relation the the noun they qualify, whereas ordinal numbers do.
Cardinal: quatre garçons, quatre filles.
Ordinal: le premier ministre, la première fois, les premiers pas, les premières études.
*un/une is slighly different since this it also doubles as the indefinite article:
un jour, une journée
Hope this helps,
Sign in to submit your answer
Don't have an account yet? Join today
Test your French to the CEFR standard