Dipole moment is a vector quantity. A 'Vector' is a Physical quantity which has both Magnitude as well as Direction. For eg. Force is a vector quantity.
Dipole Moment is a measure of polarity of covalent bond.
Covalent bonds become polarised due to electronegativity difference between atoms in which covalent bond is present.
μ is the Dipole Moment
q is the charge
d is the separation between the charges