Assuming your data has headers to identify the column names as A...X:
t1 = readtable('abc.csv');
t2 = readtable('test1.csv');
t2.F = t1.X;
If you don't want to overrwrite column F:
t1 = readtable('abc.csv');
t2 = readtable('test1.csv');
t2.newF = t1.X;
t2 = movevars(t2, 'newF', 'Before', 'F')