A confusion with power ratio jargon used in antenna directivity (dBi/dBd)
An isotropic antenna would radiate equally well (or be equally sensitive) in all directions.

A dipole antenna is directional, radiating little or no power off the ends of the element, instead directing the power at right angles to the antenna element - this results in about 2 dB more power in the favoured direction than the isotropic antenna would provide.