ELI5 explanation: Because of something called the "hairy ball theorem" [0], which says you can't comb hairy balls (but you can comb hairy donuts), scientists are making a hairy, combed, billion-dollar metal donut [1] to squish hydrogen atoms evenly on all sides. Once you turn on the machine, the squished hydrogen atoms release energy!
This news today is saying that the hairy, combed, billion-dollar metal donut is the right shape, which is very important because nobody ever made a donut like this before, and if it was the wrong shape you couldn't comb it and that means the hydrogen would escape and you couldn't make any energy.
An important thing about the 7-X is that it's not about the fusion (squishing), because fusion is fundamentally a very simple process. It's all about the combing (plasma physics), which is very difficult and the reason we don't have squishing-plants yet.
For anyone reading who don't get just how simple it is, there are literally hundreds and possibly thousands of people who have built their own DIY fusion reactors at home. Many high schoolers, some of them as young as age 14.
This news today is saying that the hairy, combed, billion-dollar metal donut is the right shape, which is very important because nobody ever made a donut like this before, and if it was the wrong shape you couldn't comb it and that means the hydrogen would escape and you couldn't make any energy.
[0] https://en.wikipedia.org/wiki/Hairy_ball_theorem
[1] http://www.sciencemag.org/news/2015/10/bizarre-reactor-might...