We are all familiar with the notion of speed, i.e. how fast something is going. Velocity is the exact same thing, except we have specified a direction. In technical terms, speed is a scalar, whereas velocity is a vector. We shall further explore the idea of a vector in the coming pages. For now, imagine it to be arrow of a given length that is pointing in a certain direction.
Given this information, you might wonder: how do we take into account the direction when solving problems? This is where the elegance of the vector is apparent. We can arbitrarily decide a "forward " direction and a "backward" direction on an axis, i.e. a straight line. Conventionally, forward is denoted by a positive value and backward by a negative value, but this too is arbitrary. All you have to do is ensure you are following the same convention throughout.