Baudrillard is perhaps best known for his notion of hyperreality, literally beyond reality, which is generally and correctly defined as 'where the representation is more real than that which it claims to represent'. We can also think of the hyperreal as being better than reality. But this is where things get a bit complex.
We live in a world saturated with media, which we increasingly use to mediate our own lives and existence. However, far from something like televised news or Instagram feeds providing a 'replacement' for reality, Baudrillard Is arguing something VERY different.
For Baudrillard, there is no reality. There has never been any reality. It is a meaningless term. The hyppereal is not, in fact replacing anything, though without a point of reference it is true that it is 'more real' than the thing it is representing. Baudrillard refers to this phenomenon as simulacra, a representation of something that never existed in the first place. And taking this to its logical end point, or perception of the world, through a saturated collection of mediated images and ideologies is a simulation.
Baudrillard uses an excellent analogy of a perfectly mentally healthy person pretending to have a mental illness. If this person lives their life pretending to be mad, for example talking to people who are not there, wearing their underwear on their head and running around like a plane from morning to night, they are, in Baudrillard's opinion, mad. There is no meaningful distinction. After all, what is being mad and what is being 'normal'? These too are societal constructs, simulacra based upon hegemonic cultural values which conveniently shift over time. In some cultures, especially ancient ones, speaking to people who don't exist could be extremely valuable, or could be extremely dangerous. And for Baudrillard, since all our societal systems have no root in any objective reality, the more we immerse ourselves in the simulation and the 'procession of images', paradoxically the more 'real' the world becomes. So basically, reality can only be formed through something being utterly irreal...
This is scary stuff! No wonder so many people end up dumbing down Baudrillard! Frankly the best explanation of the simulation hypothesis I have seen is this meme from Weird Twitter shitposter DA SH@RE Z0NE, which nicely sums up the realisation that nothing is real, and it never has been!