What does LIKE '%%' mean in postgresql?
'% %' means you are searching a String in a query with a " " space in any position. If the String don't have a space, It will not return anything.
If you want to search more about SQL Wildcard Operators, Just click the link.
The % is a wildcard that matches any character, and any number of characters. So a LIKE % matches everything. In your case, the LIKE '% %' matches anything that has a space in it.