Obamacare (the Affordable Care Act or ACA) was an attempt to expand coverage and slow the rate of increase of costs. It did the former but less well with the latter.
One other thing the ACA did is stop the scourge of scam insurers. This is a thing where people would pay for "insurance" and then find out later that their "insurance" did not actually afford them any meaningful coverage. The ACA tried to close a set of loopholes and overall regulate the insurance market more closely.
Anybody reading this from outside the US probably lives in a place where low-cost healthcare is more accessible than it is in the US.