This is the 158th most frequent Serbian word.
српска
"Српска" means "Serbian" in English.
In this case, 'српска' is an adjective describing the cuisine, specifying that the dishes are Serbian.
Она има српска јела на менију.
She has Serbian dishes on the menu.
Here, 'српска' modifies 'народна изворишта,' making it refer to origins of or pertaining to Serbian culture.
Моја мајка је изучила српска народна изворишта.
My mother has studied Serbian cultural origins.
The word 'српска' is used as an adjective referring to something belonging to or related to Serbia, here describing the flag as the Serbian flag.