A vector is just a group of numbers. That’s literally all it is.
But the most common use is to describe something in three dimensions, usually a point in 3D space (x,y,z), or motion (still x,y,z but those numbers are in meters per second or something). But you could also use it for a color (r,g,b).
But what most people mean when they say “vector” is a set of three numbers, where two are direction and one is magnitude. You know how they’re usually represented by an arrow? The direction components determine which direction that arrow points, and magnitude is the length of the arrow. (In two dimensions, this would probably be degrees of rotation and distance, like in a polar coordinate system.)
There are mathematical conversions you can do to translate one of those vectors into other forms. One popular one is a conversion to get the coordinates of the point at the top of the arrow.