Please always share code as text and not as screenshot.
%let location=%str(Buenos Aires, Argentina);
%let city=%scan(&location, 1, %str(,));
%put &=city;
The documentation tells you that %scan() allows for FOUR parameters.
The last comma in your code is not interpreted as the delimiter for the charlist but as separator for the next parameter modifier. This means that you define the value for charlist blank meaning there isn't any.
To get what you want quote the last comma so it gets used as value for charlist.
%let location=%str(Buenos Aires, Argentina);
%let city=%scan(&location, 1, %str(,));
%put &=city;