There are lots of angles on this and diffferent approaches. From my perspective, dj-ing is taking two vinyl two records and beat-matching on direct drive turntables.
If you want to learn to do this, buy turntables, start off with two copies of the same record, match those up, move outwards.
I failed to do this, I regret not doing so…
So, there are now other ways to do this, easier, Traktor, etc. But that feels like a bit of a commoditised game to me, personally.