From this pls where did you get zero or what does zero represent,pls explain the solved example again in English

The example complex ion was [Cu(H₂O)₆]²⁺.

The central metal ion is Copper (Cu). In this specific complex, its charge is +2 (written as Cu²⁺). This is often given or can be deduced from the overall charge of the complex if you know the ligand charges.

The ligand is water (H₂O). A water molecule is neutral, meaning it has no overall charge. Therefore, the charge of one H₂O ligand is 0. This is where the "zero" comes from.

To find the overall charge of the complex ion, we add the charge of the central metal ion to the total charge contributed by all the ligands:
Overall charge = (Charge of central metal ion) + (Number of ligands × Charge of one ligand)
Overall charge = (+2) + (6 × 0)
Overall charge = +2 + 0
Overall charge = +2

So, the zero represents the neutral charge of each water molecule (H₂O) acting as a ligand.