What does the following reaction show for H₃BO₃ [i.e., B(OH)₃] ?

$\mathrm{B}(\mathrm{OH}{)}_3+2\mathrm{HOH}⟶{\left[\mathrm{B}(\mathrm{OH}{)}_4\right]}^{-}+{\mathrm{H}}_3^{+}\mathrm{O}$

Ortho boric acid is a weak mono basic acid. It is lewis acid but not protic acid.

It accepts an electron pair from ${\mathrm{OH}}^{-}$ of water and releases ${\mathrm{H}}^{+}$