Playout is an old broadcast word for the last thing that happens before a channel leaves the building. Somewhere between the archive and the transmitter, a schedule has to become a single unbroken stream: the 8pm show has to start at 8pm, the logo has to be in the corner, the ad break has to be marked so it can be sold, and the whole thing has to be encoded into something a viewer can receive. The room where that happened was called master control, and it was full of expensive, specific hardware.
Cloud playout is that same chain, running on infrastructure you never see or maintain, driven from a web console. Nothing about the broadcast requirements changed. What changed is that the four jobs below stopped being four purchases plus an integrator, and became a subscription with a login.
That distinction matters when you are comparing products, because plenty of things marketed near this term are not playout. A video host that loops a playlist has no schedule, no graphics, and no ad signalling. A live production switcher needs an operator for as long as the show runs. Playout is the automation that keeps a channel on air for a year without anybody sitting at a desk.