In Dynamo Vectors typically are used to describe a "direction". . for example if you are defining a structural framing member's up vector to point up in the "z" direction. then you would say vector = 0,0,0
meaning ... 0i, 0k, 0k which is the same as saying 1i, 1j, 1j
also note that vectors are defined as i, j, k which refer to the "x,y,z components" of a location in 3-d space respectfully.
Still confused? just remember two things
1. Vectors are NOT points even though they are defined the same
number, number , number
2. Vectors define direction using the "right hand rule"
maybe the image below will help
I hope that clarifies vectors a bit now go out and make some dynamo vectors!