This is the 473rd most frequent Czech word.
programu
"Programu" in Czech means "of the program" or "to the program" (genitive or dative singular of "program").
In this sentence, 'programu' is in the genitive singular form to describe partitive or in association with the program that took place.
Účastnil jsem se zajímavého programu v knihovně.
I participated in an interesting program at the library.
'Programu' here is used in the genitive case as it indicates to which entity the 'content' belongs.
Obsah programu byl velmi informativní.
The content of the program was very informative.
Here, 'programu' is in the genitive singular form and is used to denote possession or relation to 'program'. It works within the structure of describing what was installed.