Why do $\text{HCl}$, ${\text{HNO}}_3$ , etc. show acidic character in aqueous solutions while solutions of compounds like, ${\text{C}}_2{\text{H}}_5\text{OH}$ and glucose do not show acidic character? Why does an aqueous solution of an acid conducts electricity?

A substance will show acidic character if it gives ${\text{H}}^{+}$ ions when dissolved in water. Among these substances $\text{HCl}$ and ${\text{HNO}}_3$ provide ${\text{H}}^{+}$ ions whereas ${\text{C}}_2{\text{H}}_5\text{OH}$ and glucose do not give ${\text{H}}^{+}$ ions. So they do not show acidic character.
Aqueous solution of an acid conducts electricity because it dissociates to produce ions.