It's striking how someone who claims to be "pretty good at scripting" has such a hard time following this very basic piece of code.
Look up in the mIRC help file what each of the commands does. I suppose the most confusing for you is the fact that the $findfile identifier has a command parameter, which will execute the command for each file name matched. Or is it perhaps the $mid that is confusing? Maybe the .echo -q ?
This is all in the help file, /help $findfile, /help $mid, /help /echo and look up the q flag.
As far as making the script "easier", there is really not much ways. $findfile is necessary, so we can't skip that. /play is suited very well here, or you'd need to loop manually through the text file, which is really not simpler, in fact it makes the script more complex, and not to mention less efficient. You're just going to have to do the effort to look up the things mentioned in the help file, and learn new things while you're at it.
Omg, how the heck do u write so long lines ?
Well, when I don't know about an identifier or alias or other thing about mirc, I use /help before asking, but I usually don't need it