Trying to combine two data frames

I’m trying to combine two dataframes. This is my code:

x = df.loc[df['continent'] == 'South America']
y = df.loc[df['continent'] == 'North America']
Americas  =x + y
Americas

When this prints, it just gives back NaN values

>Solution :

By combining, if you meant appending; then try this… means daya y below data x;

Americas = pd.concat([x,y])