What are generators and why do they stop?

Generators (like the Drinks Cart or Lemon Tree) are the items that produce things when you tap them. Each tap costs energy. After 10 quick taps a generator rests for a bit — that's a short breather, not a problem. If you have energy, you'll never be blocked for long. Some generators arrive locked, in crates, or needing repair — that's story progression; keep playing the chapter and they'll open.