If you master this, you'll immensely expand your vocabulary. These prefixes are often used with verbs. So, it is important that you know as many verbs as possible. They're ones of the verb nominalizers.
Thai and Lao use nák- (นัก), phûu- (ผู้), and khon-(คน) to convert a verb to the verb in question's doer. Shan however only uses the last two prefixes.
In Thai and Lao, the diference between nák- and the other two is that nák- when combined with a verb is often used to indicate the doer's profession. In other words we can also tell that the doer does the action as a profession.
In Shan, phûu- unlike Thai and Lao is used pretty much like nák-, and khon-(kon-) is used more or less like the Thai and Lao khon-.
Formula: nák-, phûu-, or khon- + verb
Thai and Lao:
khìían "to write"
nákkhìían "writer" (profession)
phûukhìían, khonkhìían "writer" (general)
hian "to study"
phûukhian, khonhian "learner"
lîk "to write"
phûlîk "writer" (profession)
NOTE: In many cases ALL of these prefixes are used interchangeably! Some people don't use nák- to indicate a profession.
Now can you covert read, walk, and run into reader, walker, and runner in these three languages?