Queso is the Spanish word for cheese, however, it has multiple meanings in different contexts and can actually refer to a particular Mexican dish known as Mexican Cheese Dip.
Queso manchego quite simply means manchego cheese. This cheese is made in the La Mancha region of Spain and is created using milk from a breed of sheep known as the Manchega breed, which gives the cheese its name. This is a key difference between manchego and parmesan, as parmesan is made using cow’s milk and is traditionally made in northern Italy. Manchego is usually aged for anywhere around 60 days to 2 years, and the amount of aging will often affect the quality of the cheese and its flavor profile.