Those people who possess favorable traits, contributing to their culture, or those do good things and not bad ones. The make-up of a 'decent person' will vary with the opinions of the speaker. For example, to one person it may be someone who is friendly and has compassion, someone who never talks, or, in which case the speaker has a mild narcissistic or tribal streak, someone who shares the speaker's religion, hobbies, habits or anything else.