Think of pH 7 as a completely balanced seesaw where the acidic forces and basic forces are in perfect equilibrium, just like pure water having equal parts acid-forming and base-forming ions.

Pure water undergoes autoionization to a very small extent, producing equal amounts of hydronium ions ($H_3O^+$) and hydroxide ions ($OH^-$). At 25°C, the ion-product constant of water ($K_w$) is $1.0 imes 10^{-14}$, leading to a hydrogen ion concentration of $1.0 imes 10^{-7} \text{ M}$ and a corresponding pH of 7.

Remember that pH is temperature-dependent; pure water can have a pH lower than 7 at higher temperatures while still remaining neutral due to changes in $K_w$.