weeds. The potting mix/mulch you used or something inside it you added was not sterile and had weed seeds. Could also be seeds blowing aorund with wind or bird poop.
"weed" as in a unwanted plant, not "weed" as in slang for cannabis.
Just pluck em and continue on.
Good Luck!
Hola es hierva silvestre. puede que tu sustrato vino con alguna semilla o alguna raíz y las condiciones de cultivo hacen que esta también crezcan. No es para preocuparse, esto da a entender que tu sustrato es fértil. Buena suerte
Seeds might have been in your soil waiting for some water to sprout. I'm not sure what those are since because most plants start off from just 2 leaves.
Good luck with the rest of your grow