Complex sentence: Leakage inductance is the property of a mutually-coupled transformer that manifests self-inductance in series with each of its windings due to imperfect coupling of the windings and creation of leakage flux which does not link with all the turns of the winding.
Split into simpler sentences: Leakage inductance is the property of a mutually-coupled transformer that manifests self-inductance in series with each of its windings. This is due to imperfect coupling of the windings and creation of leakage flux which does not link with all the turns of the winding.