IMPORTANT NOTE: Please check the below document, before you start customizing your environment.
Holding a prereq procedure for a best control over your customization.
KB000125335
https://comm.support.ca.com/kb/important-notice-of-prereq-for-customization-on-ca-service-catalog-files/KB000125335
 

N/A

Windows

This string is set/defined in the "catalogbrowse.xml" and some other files (see below). 
For the U.S. English language, this file is located in folder: 
"%USM_HOME%\view\webapps\usm\locale\icusen\request". 
 
IMPORTANT NOTE! 
Do not change the ootb delivered file. But a copy of it in stead in the 'filestore' folder tree.

The steps to be taken then are described below.
1. Copy the following files:
a. catalogbrowse.xml 
b. cataloggetchildren.xml
c. catalogitemdetails.xml
d .webstorebrowse.xml

from "%USM_HOME%\view\webapps\usm\locale\icusen\request"
into "%USM_HOME%\filestore\custom\locale\icusen\request" (when not existing already, you need to create this path).

2. Open(notepad) the the copy of the files.
Change the text between the tags to the new value you would like to use:
 <unknown>Not Categorized</unknown>
 <unknown_description>Catalog services not categorized.</unknown_description>

3. Save the changed files.

4. After saving the changes, you will need to restart the catalog service for them to take effect.
a. Stop the CA Service Catalog services(Accounting and Catalog)
b. Empty/clear the %USM_HOME%\view\translets folder
c. (re)move the %USM_HOME%\logs\*.log files
d. Clear the browser-cache
e. Start the CA Service Catalog services(Accounting and Catalog)

Note:
The breadcrum should then contain the changed folder name "Not Categorized xx" too.