The analogy is meant to show parallels between two sets of words. Fertile is to arable as vague is to clouded. If you understand either pair it can be used to decipher the meaning of the other pair you don't know.
Peio is a comune in Trentino in the northern italian region Trentino-Alto Adige/Süditrol, located about 50 kilometres northwest of Trento
:)
The following is the first one