A KA prefix can mean many different things;
1) when prefixed to a noun, it implies a companion or partner, e.g. kasama - companion, kaklase - classmate
2) when prefixed to a verb root that repeats the first syllable it implies repeated action, e.g. kakukuha - continuous taking, kasisigaw - continuous shouting
3) when prefixed to a verb root that repeats the first syllable and followed by lang it implies recent action, e.g. kaaalis lang - just left