Unsupervised learning means to "explain" complex or unknown data in a way that is objective, independent yet relevant.
For example, shop owners try always to learn new ways of increasing the profit by watching the passers-by in search for new ideas – an idea such as street attraction during vacation times, a need for a quick service in rush hours, offering help to window shoppers, etc. A fresh and objective look on unfiltered data is the key for useful indications that can be acted upon.
Many practical ideas can be found methodologically by analyzing available unsupervised data.
Unlike supervised-learning that pre-assumes much of the information about variables, in unsupervised learning one acquires new understanding regarding variables as well as cluster formation, alerts and farther insights.