Gena is correct about the literal meaning. "Stays" were originally long strips of whalebone in a corset, and the corset would be "laced" or tightened up to prepare a woman for the day ahead. So, when used as a metaphor or idiom, "lace your stays" means - "get ready for action!", "prepare yourself!", "make yourself socially presentable". "Gird your loins" means the same thing..... Desculpe, não posso explicar em Português ....:-(

It sounds like it means to lace up some shoe strings or to lace the stays in an old fashioned woman's corsette or girdle, like they did in the olden days, like 60 years ago and earlier. Women used to wear girdles that would lace up. I think they had plastic "stays" that kept the girdle rigid. Mayb before plastic was available, they even used bones. That's the only meaning I can think of.