In Spanish, names of things (nouns) and words that describe those things (adjectives) need to match. They need to agree in two ways: gender and number.

Let's break it down:

1. Gender Agreement:

   • Masculine nouns usually end with -o.
     For example, "niño" means boy. So, you would say "niño feliz" which means happy boy.
   • Feminine nouns usually end with -a.
     For example, "niña" means girl. So, you would say "niña feliz" for happy girl.

2. Number Agreement:

   • Singular nouns just need the describing word (adjective) to stay singular.
     For example, "libro interesante" means interesting book.
   • Plural nouns change the describing word by adding -s or -es.
     For example, "libros interesantes" means interesting books.

3. Exceptions: Some describing words look the same for both boys and girls.
   For example, "estudiante inteligente" means intelligent student, and this works for both a boy and a girl.

So remember, to speak clear and correct Spanish, make sure the noun and adjective match in gender and number!