The journals have an "impact factor", an arbitrary metric that determines how noteworthy they are. My impression is that very few journals are actually read directly - most papers are found via Google Scholar and the journal they're in doesn't matter.

However, in academia, the "prestige" of the journals you have published to is hugely important. Good journals, in theory, are more selective about what they publish, so the assumption is that if you have publications in a good one you must have done more groundbreaking research. To an academic, this is the kind of thing that affects whether you get grants, whether you get paid more, whether you can get a job elsewhere.

Some journals are pretty much talked about in hushed whispers, like "that PhD student got an ___ paper in their first year, they must be some kind of genius". In reality, research tends to be more about who you know, what kind of work you're doing, and whether you're in the right place at the right time.