${\mathrm{H}}_{\left(\mathrm{aq}\right)}^{+}+{\mathrm{OH}}_{\left(\mathrm{aq}\right)}^{-}\to {\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}$
$\mathrm{\Delta H}=-\mathrm{ve}\text{ and }\mathrm{\Delta G}=-\mathrm{ve}$, then the reaction is

For a spontaneous process $∆\mathrm{G}=-\mathrm{ve}$

The given reaction represents neutralization reaction 

neutralization reactions are instantaneous reactions