For loop is taking to much time to run, is there a simpler way of doing this by the use of any function?

Question

I have found a way to loop through all the values of a column in dfA and when the value is equal to tha same column in another dataframe dfB, to take the value of ColumnB of dfB to ColumnB of dfA. This is taking a lot of time to run and i suppose there is a simpler way to do it with the use of some functions??

My for loop looks like this and is working:

for x in dfA['ColumnA']:
    if (dfB['ColumnA'] == x).any():
        dfA1['ColumnB'] = dfB['ColumnB']