If the option Find objects with text is selected, you can enter some text to search for. The following check boxes define where the search action searches for occurrences:
in their name
You can find objects that contain the search text somewhere in their name. For instance, a document with the name 'list payments' will be found if you search with the search text 'payment'.
in their description
Objects that contain the search text in their description will be found.
in their content
This performs a full-text search for the search text in the content of documents and Text Blocks. To determine whether the search text is present in the object, it's current revision is inspected. If you have locked the object yourself, the in-development revision will be used instead. You can also search for Field names that are used in Text Blocks.
You can combine these check boxes in several ways. The result will be a combination of objects that contain matches with any one of the options.