Statement-1: Boric acid is a weak monobasic acid. 

Statement-2: Boric acid has only one replaceable H-atom.

Boric acid $\mathrm{B}(\mathrm{OH}{)}_3$ is a monobasic acid. It is an oxy acid, as evidenced by its structure. However, none of its OH generate${\mathrm{H}}^{+}$. However, even after bonding with 30H, boron has a vacant p orbital. So, in water, ${\mathrm{H}}_2\mathrm{O}$, a lone pair is donated to $\mathrm{B}(\mathrm{OH}{)}_3$, and it forms a Corordinate bond with ${\mathrm{H}}_2\mathrm{O}$. As a result of donating its lone pair, 0 receives a positive charge. However, because OO is an electronegative element, positive charge is not stable on it. As a result, a proton ${\mathrm{H}}^{+}$ is removed from it, and $B(OH{)}_4$ with a minus charge is formed, yielding a ${\mathrm{H}}^{+}$. As a result, it is a monobasic acid.