You can hide files in a view by applying a filter or mask:
You can apply a mask from the Display tab. You can use a mask amongst others to quickly check if a new filter that you are creating behaves as intended.
From a view with a mask you can use the "Rescan with mask as filter" option from the main menu to create a new window with the mask used as filter. You can also use the Filter command from the "Window" menu to apply a filter to an existing view. It is similar except that it does not rescan your disk and lets you select a different filter if you want.
Use the Filtered scan command from the "File" menu if you want to apply a filter when scanning new data. A filter used this way can greatly speed up scans by skipping folders that you are not interested in.
In the Preferences you can also specify a default filter. This filter is used when scanning unless it is explicitly disabled. It can be disabled by carrying out a filtered scan and disabling the option to apply the default filter.
How packages are filtered depends on whether their contents are shown when the filter is applied. If their contents are shown, the package itself is treated as a folder and the filter is applied to all files inside the package. Otherwise, the package is treated as a file by the filter and omitted or included as a whole. When applying an additional filter to an already filtered view, the original filtering logic is used irrespective of the current display settings.