It means, to put it bluntly, that it's got holes in it. Like lace or crochet or mesh, in a way, but in principle troquelado means that the holes are cut. Often done with lasers these days, apparently. So "pierced". It seems "perforated" is used a lot for this.

Here are some "blusas troqueladas":
https://www.chicfy.com/blusa-troquelada-zara/agotada-blusa-b...
https://www.elcorteingles.es/moda/A19823613-blusa-troquelada...
https://pedrodelhierro.com/es/es/mujer/blusas/blusa-troquela...

The Pedro del Hierro one is called "die-cut" in the English version:
https://pedrodelhierro.com/gb/en/women/blouses/die-cut-blous...

But that doesn't seem to be used much. "Perforated" is what I mostly find for this:

"The finer point we're focused on is perforated fabric-meaning: pierced, hole punched, or laser cut-a trend that's making a big statement this season."
http://www.whowhatwear.co.uk/go-buy-now-perforated-pieces

" I like solid colors and clean lines, but sometimes that can get boring if you don't throw in a little twist. The newest new way to add dimension to an understated look is with perforated clothing. Deborah Boland -perforated peach top. I touched on perforated tops when I wrote about eyelet."
https://www.fabulousafter40.com/perforated-fashion-trend/

"Keep cool this season with the must-have summer fashion trend of perforated clothes and accessories for men and women."
https://www.timeout.com/newyork/shopping/beat-the-heat-with-...

Quite a lot of perforated blouses out there if you look.