Adjectives can occur before nouns.
the old wall
"old" is an adjective.
Adjectives can be changed into comparative and superlative forms.
the older wall
the oldest wall
With adjectives of more than one syllable, "more" and "most" are used instead of the suffixes "er" and "est".
the more beautiful wall
the most beautiful wall
Adjectives can also be used after "be"
the wall is old
this wall is older than that one
Nouns can also occur in the same position as adjectives.
the stone wall
"stone" is a noun. We know it's a noun because we cannot add "er" like we can with adjectives:
*the stoner wall (wrong)