The rules are exactly the same as those used to form the plural of nouns. To illustrate this, we would say for a sentence like “It`s a nice model” “Ella es una modelo hermosa”, but for several models we have to say “Ellas sound without hermosas mode”. Note that all words, including the subject pronoun and the SER verb, change, so there is indeed a Spanish subject-adjective correspondence and the sentence has meaning. In sex, most adjectives must match the noun they change. If we describe a masculine noun as “Amigo”, we must also use a masculine adjective as “Honesto”. As with nouns, Spanish masculine adjectives usually end on the -O vowel such as “Bonito” and “Creativo”, z.B. “El niño es bonito y gordo”. In addition, some words that end on -R are also considered masculine adjectives. On the other hand, to describe female nouns such as CASA (house), we need to use a feminine adjective like BONITA (pretty) or ESPACIOSA (spacious) and not masculine nouns like BONITO or ESPACIOSO….