This is the 10176th most frequent Russian word.
бессмысленную
"Бессмысленную" means "meaningless" in English.
In this sentence, the word 'бессмысленную' is used to describe the argument ('ссору') as being pointless or futile.
Они начали бессмысленную ссору.
They started a pointless argument.
In this usage, 'бессмысленную' is used to qualify the work ('работу') as lacking sense or purpose.
Я не хочу тратить время на бессмысленную работу.
I don’t want to spend time on meaningless work.
Here, 'бессмысленную' modifies 'вещь', indicating that the object was deemed to have no value or meaning.