Yugi is very familiar with crafting! At least, as much as it extends to video games mechanics. Or, maybe fusing monsters in a card game would be similar enough? Point is, Indigo doesn't have to explain the concept to him, outside of of perhaps explaining what in fact she is trying to craft.

"I've been here for a while looking for things that seem interesting, but if you need a second pair of eyes I can keep a look out," he offers, looking rather excited about the prospect. "Raw materials like iron? I've seen scrap metal around..."