The text that displays when there are no locations to be displayed can be changed under Settings/Results in the section under Appearance. Type a message in the box to whatever you want the site visitor to see when there are no results found.
Example of the text added under the SLP Settings/results and how it appears to the site visitor front end when no locations or results found:
There are five sections under the Settings/Results tab admin panel. Each section describes when and/or where the results will appear under your map.
You determine the Number of results you want to appear on the map and locator page as soon as the page loads when you have “Show locations at startup” checked. We recommend 50 for most sites unless you have the Premier add-on which allows less clutter by virtue of cluster markers.
The next setting is the radius to search initially when “Show locations at startup” is checked. Leave empty to use the map radius default. Set to a large number to search everywhere.
With the Experience add-on, (or if you are using MYSLP, the Professional level plan) other settings will appear and can be enabled that will Not show the results immediately until after a search has been performed. The setting is labeled “Disable Initial directory”.