Boiadeiro refers to a cowboy or cattleman, someone who works with cattle. It's a word deeply rooted in Brazilian rural culture, especially in the sertanejo music genre.
In this song, "a voz do Boiadeiro" (the voice of the Cowboy) is presented as something powerful and enticing, making "novinhas" (young women)
Get ready for a party in the Brazilian countryside! "Chá do Mato" paints a picture of a scene where the music is turned up loud with heavy bass, and the "Boiadeiro" (cowboy) is the center of attention. The song describes a new trend spreading from the interior of Brazil to the rest of the world.
The lyrics tell a story of young women leaving the city behind, drawn to the farm life. They are described as being "addicted to the cowboys" and coming to the countryside just to "gallop." The singer's voice gives them shivers, and they want to get close, embracing the wild, rural atmosphere of the "mato" (the woods or countryside).