What does Qemau mean in Egypt?

Ancient Egyptian writing did not record vowels, only consonants, so it is difficult to know which Word you mean.

There is a Word qmAw (the A is a catch in the throat, not a vowel) that means a winnower: someone who winnows wheat to remove the inedible bits.

Another qmAw indicates a type of soldier; it uses the base Word qmA, meaning to throw, so perhaps they were light troops armed with javelins and deployed as skirmishers ahead of the main army.