How will you account for the acidic nature of carboxylic acid ?

Explanation

In case of carboxylic acid resonating structure are as follows:

Now as positive charge is on O-atom so it attracts the electron of O-H bond towards itself. As a result O-H bond weakens and ultimately breaks giving proton.

Now as the resulting carboxylate anion (III) is more stable as compared to carboxylic acid. So carboxylic acid is acidic.
Resonating structure of carboxylic anion making carboxylate anion stable.