His name comes from the Greek word for "honey," which is common image in pastoral poetry, and Meliboe really is a sweet guy. He's father of Pastorella and host to Calidore. Meliboe offers the most sustained praise of the pastoral life, describing how even he left his life as a shepherd to pursue the glory of knighthood, only to tire of that life and return to the life of a shepherd.
For Calidore, who is already starting to doubt his chosen path, Meliboe's experience has a big impact on Calidore's choice to suspend his quest for the Blatant Beast. However, Meliboe also cautions Calidore against ignoring the role that nature has allotted for him, advice that Calidore doesn't fully listen to. Meliboe's ability to not only champion the simple life, but to also understand the value of all different life paths, shows him to be more than a spokesperson for the pastoral but truly wise.