Okay, let's do the basics:

A DAC is a digital-to-analog converter. If you use a digital thing (TV, tablet, phone, computer, Cd player, basically anything that isn't tape or vinyl) you need to do this step to produce an analog sound.

If you want to then hear the sound, it needs to be amplified. A DAC doesn't produce an audible signal on its own.

Neither is very difficult to do these days - the dongles that some phones have included often do both.

There are many, many DACs and amplifiers you could buy. It depends heavily on what you want to spend on them. One option per example: FX-AUDIO DAC-X6 MKII