1. Rood: This could possibly be a brand name or a model name of the bicycle. Without specific context, it’s challenging to determine precisely what “Rood” refers to, but it likely identifies the brand or model of the bike.
2. 26in: This indicates the wheel size of the bicycle. A 26-inch wheel size was once very common for mountain bikes and some hybrid bikes, though it has become less prevalent in recent years with larger sizes like 27.5 inches and 29 inches gaining popularity.
3. 21 Speed: This denotes the number of gears or speeds the bicycle has. A 21-speed bike typically has three front chainrings and seven rear cogs, providing a wide range of gear ratios for various riding conditions.

Therefore, “Rood 26in, 21 Speed Bike” describes a bicycle branded as “Rood,” featuring 26-inch wheels and equipped with a 21-speed drivetrain system. It suggests a versatile bike suitable for different terrains and riding preferences.