なん + counter + か

This form combines なん (a phonetic form used before counters) with a counter followed by か to express an indefinite, small quantity of something, similar to 'some' or 'a few' in English. It is more formal or literary than using 何 + counter + か in everyday speech. It is typically used with counters like 本, 枚, 匹, 冊, etc., when the speaker wants to emphasize that the exact number is not stated. The なん- form tends to appear in written language or careful speech rather than casual conversation. Note that なん can be heard as 何 before some counters in casual contexts, but なん + counter + か has a distinct nuance of an approximate, unspecified amount.