If I say Height of a block = 2m, then would "Height" be called as a dimension
Casually I would say the dimensions are
TIME (and others). A unit is a metric (yardstick) to measure said dimensions. So one meter (unit) is used to quantify a specific length (dimension).
This allows the combination of dimensions through multiplication and division to derive other units such as
Speed = Meter/Second => LENGTH/TIME