Today's Parola del Giorno is the expression, non capire un'acca, which means to be unable to make heads or tails ofsomething.
The word, l'acca, is the letter, H, (which is silent in Italian), having slowly lost its pronunciations from Latin and so the expression is used to say that one does not understanding something.
See the expression used below:
Nonostante abbia seguito con estrema attenzione il corso per imparare ad usare Microsoft Excel, non ci capisco ancora un’acca
Even though I paid close attention to the course so I could learn to use Microsoft Excel, I still can't make heads or tails of it.