Hi @JS-JS ,
I've made a test for your reference:

1)
add(items('Apply_to_each'),1)
2)
length(split(outputs('Get_item')?['body/column1'],decodeUriComponent('%0A')))
3)
concat(
items('Apply_to_each'),
') ',
split(outputs('Get_item')?['body/column1'],decodeUriComponent('%0A'))[items('Apply_to_each')],
'-',
split(outputs('Get_item')?['body/column2'],decodeUriComponent('%0A'))[items('Apply_to_each')],
'-',
split(outputs('Get_item')?['body/column3'],decodeUriComponent('%0A'))[items('Apply_to_each')],
decodeUriComponent('%0A')
)
The Result:

Best Regards,
Bof