SAP quickviewer is the small sister of SAP query and allows querying SAP's wealth of tables in a user friendly (end user ready) toolset. Transaction SQVI will take you there.
End users that use SAP query as well as QuickViewer will notice the similarities. It is less powerful than SAP query, yet also a little less complex. If you need your QuickViewer query to be migrated to other systems - consider transforming the SQVI query into a SAP Query. SQ01 Menu: Query > Convert quickview.
Much more on how to use the Quickviewer on scn.sap.com.