The particles in the beaker are in motion. Hydrochloric acid drops in as H⁺ and Cl⁻, sodium hydroxide as Na⁺ and OH⁻. When an H⁺ meets an OH⁻ the pair becomes water and disappears.
The panel names at the top right open and close each panel. The buttons add sodium hydroxide and hydrochloric acid, and reset returns the beaker to its starting state. Drag a panel by its header to move it.
The equation is HCl + NaOH ⟶ NaCl + H₂O, but the only things that change are H⁺ and OH⁻. Remove Na⁺ and Cl⁻ from both sides and H⁺ + OH⁻ ⟶ H₂O is what remains. That is what neutralization is.
Na⁺ and Cl⁻ do not react. They stay in solution, and evaporating the water leaves sodium chloride behind. That is the salt.
The state of the solution follows the counts: more H⁺ and it is acidic, more OH⁻ and it is basic, equal numbers and it is neutral. What is counted here is the particles on screen, not a concentration.