Hi,
This is a server wide file and can be edited if you have back-end access.
The file is located in $SEARCH_HOME/web/templates/modernui/
If you wish to customise this make a copy of the file
$SEARCH_HOME/web/templates/modernui/no-collection.default.ftl as $SEARCH_HOME/web/templates/modernui/no-collection.ftl and edit the copy ($SEARCH_HOME/web/templates/modernui/no-collection.ftl).
Note: Don't edit the $SEARCH_HOME/web/templates/modernui/no-collection.default.ftl file otherwise this will be replaced when you upgrade Funnelback.