What is lorem ipsum?
Scrambled Latin-like placeholder text, used since the 1500s by printers and typesetters. It looks like real text, so a layout can be judged by its design without readers getting distracted by the words.
Does it mean anything?
Not really. It comes from a passage by Cicero, but the words have been shuffled and altered so they no longer form meaningful sentences.
Should I use real content instead?
When you can, yes. Real text reveals problems lorem ipsum hides, like long headlines or translations that run longer. Placeholder text is best for early layout work.