Translated carne seca means "dried meat". Thin strips of dried, salted beef essentially the same as beef jerky found in the U.S. Buy good quality jerky not the reconstituted snack form found in many grocery stores. It is best purchased from a meat market or butcher that makes their own.
Carne seca is used in dishes like Machacado con Huevo (crushed meat with eggs). The jerky is typically roasted then shredded and sometimes soaked before use. In Mexico the dried meat is sometimes seasoned with lime, salt and dried oregano, and sometimes with dried chile.