How does Helium mining actually work? Is it still worth it?

I keep hearing about "Helium mining" and people setting up little hotspots to earn HNT. I understand Bitcoin mining with ASICs, but this seems completely different—something about providing wireless coverage? Can someone explain in simple terms what you're actually doing when you "mine" Helium, what hardware you need, and if it's still a viable thing to do now that the network has transitioned to Solana?