What do you understand by their term vector speed?

Vector is used mostly in physics when referring to quantities that have both magnitude and direction. Speed is also a term in physics which means the total distance covered by an object with respect to time. Speed is not a vector quantity but a scalar quantity. It has only magnitude but no direction. If you are calculating the speed of an object moving from one point to another, you can only get the distance covered and not the course of the object.

That's why the speedometer in your car can only measure the speed with which you are moving and not the direction you are going to. Vector quantity does not determine your location but the direction you are moving to. Quantities like velocity, acceleration, etc., are vector quantities because their magnitude can be calculated, and their direction can also be determined. The 'direction part' is always the difference between speed and velocity

Vector is a term used in physics that combines both a magnitude (or size) and direction (which way the object is moving). It does not have a location, however. It is usually noted through an arrow, which gives the direction that the object is traveling. It will never denote a specific area. There are several mathematical manipulations that can be used to estimate vector speed. Division, multiplication, and subtraction are just a few.

Vector speed is a bit different from normal speed. While a regular speed takes into account the magnitude, it does not account for the direction. This is where vector speed is calculated, adding in the dynamics of the direction in addition to the magnitude of the moving object. Vectors are considered simple and very useful when it comes to calculating and estimating different rates of speed. What we call vector speed was not mathematically coined until the late nineteenth century.