You have to supply your own box/stick. Most recommended are, in no particular order, a Roku streaming stick or an Amazon Fire Stick. There are also the “Google Chromecast with Google TV” or the Apple TV box. All those I’ve mentioned support the Now app.
NOW is a streaming service, similar to Netflix or Disney+ etc
They used to sell Roku powered streaming devices however these were discontinued a few years ago. If your Smart TV hasn’t got the NOW app available you could get a Fire TV, Apple TV or something similar. Check the link for compatible devices