Think of a neutral solution like a perfect balance scale where the 'acid' side and the 'base' side carry identical weight, resulting in a state of equilibrium.

7 is the Heaven of neutrality: neither acidic nor basic.

The pH scale is defined as the negative logarithm of the hydrogen ion concentration, expressed as $pH = -\log[H^+]$. In pure water, water molecules undergo auto-ionization ($H_2O \rightleftharpoons H^+ + OH^-$) to produce an equal number of ions. Since the ionic product of water ($K_w$) is $1.0 \times 10^{-14}$ at $25°C$, and $[H^+] = [OH^-]$, then $[H^+] = \sqrt{10^{-14}} = 10^{-7} M$, leading to $pH = -\log(10^{-7}) = 7$.

Always remember that pH is a logarithmic scale; a change of 1 pH unit represents a ten-fold change in $[H^+]$ concentration.