WHAT DOES TRANSFORMER 277V TO 240 V MEAN?

will they be as reputable and as pure as feeding actually 220v towards the amps? many thanks and sorry if I appear to be trolling with these 'my dad's shopping for me a chinese amp!' threads but This can be the only day he can do this cuz of his program plus the window of time is closing...Purchased transformers to make use of on our industrial equ