OLAP is a way of constructing queries and persisting/refreshing their results. Some OLAP based systems have a query designer where you can drag and drop columns, set values for certain columns to reduce the data, aggregate certain columns or pivot certain columns. They also have special handlers for pivoting such as pivoting datetime columns by a given granularity.

All these reports can be kept up to date in a live fashion by the OLAP service as new relevant data comes in, much like a materialized view.

Many accounting systems support OLAP based queries in order for the accounting department to design reports and export them to excel.