This is the 96th most frequent Czech word.
všechny
"Všechny" means "all" or "everyone" in English.
The word 'všechny' is used here as a demonstrative pronoun meaning 'all' and agrees in number and case with the plural noun 'knihy' (books).
Všechny knihy jsou na stole.
All the books are on the table.
In this example, 'všechny' is used as a pronoun referring to people and denotes the meaning 'all (of them)'.
Viděla jsem všechny, jak odcházejí.
I saw all of them leaving.
The word 'všechny' functions as an adjective modifying the plural noun 'problémy' (problems), meaning 'all' in this context.