This is the 131st most frequent Polish word.
kilku
"Kilku" means "a few" or "several" in English.
Here, "kilku" is used to mean "a few" and it modifies the plural noun "znajomych," specifying an indefinite small number of friends.
Zaprosiłem kilku znajomych na imprezę.
I invited a few friends to the party.
In this sentence, "kilka" again means "a few" but refers to "minutes" (an amount of time), highlighting an approximate short duration.
Rozmawialiśmy przez kilka minut.
We talked for a few minutes.
Here, "kilka" is used to indicate an indefinite small number of "pomysły" (ideas), showing the speaker's possession of multiple but not many project ideas.