The guiro is a notched hallowed - out gourd and is a member of the percussion family. The guiro is played by holding the guiro in the left hand with the thumb inserted into the hole. The right hand holds a stick and scrapes against the guiro to get a raspy sound.
Guiros can be made of wood, metal, shell, bamboo, plastic, ceramic, or bone. The guiro is played in Salsa and Spanish Folk music. (http://www.musicofpuertorico.com/index.php/instruments/guiro/)
Here is an example of what a guiro sounds like: