repeat-an-edit-on-multiple-lines

https://stackoverflow.com/questions/355907/how-do-i-repeat-an-edit-on-multiple-lines-in-vim

1

for the text:

abc123abc
def456def
ghi789ghi

you do:

Ctrl - v
jj # select 3 lines
Shift - I
, # insert a comma
Esc # at this moment, three commas gonna be added

you get:

abc,123abc
def,456def
ghi,789ghi

2

use ctrl + v to and move cursor, you'll select several lines, you can do operations in normal mode, for example x to delete a character.