This is the 2349th most frequent Swedish word.
dyra
"Dyra" means "expensive" in English.
Here, 'dyra' is an adjective describing 'smycken', indicating that the jewelry is costly.
De har köpt dyra smycken inför festen.
They have purchased expensive jewelry for the party.
In this sentence, 'dyra' is used nominally to denote the general concept of expense, emphasizing the costliness of restaurants.
Att restauranger kan vara så dyra är verkligen förvånande.
That restaurants can be so expensive is truly surprising.
'Dyra' functions to describe 'saker', identifying the types of things, specifically that they are costly.