Learn Italian: Perché non capisci il problema? - Why don't you understand the problem?

Capire (to understand) belongs to a special group of -ire verbs that need an extra -isc- added into the middle of the word for most forms in the present tense. For the "you" (singular) form, we take the stem cap-, add -isc-, and then add the usual "you" ending -i, making capisci.

How do you pronounce the "sci" in capisci?

In Italian, when the letters sc are followed by an i or an e, they make a "sh" sound, just like in the English word "sheep". So, capisci is pronounced "cah-PEE-shee".

Why does it say il problema? Doesn't the -a ending mean it should be feminine?

Normally, yes! Words ending in -a are usually feminine. However, problema is a famous exception. Words that end in -ma and come from ancient Greek are often masculine in Italian. Because it is masculine, it takes the masculine word for "the" (il) and changes to i problemi in the plural.

Where is the word for "you" in this sentence?

In Italian, you usually leave out subject pronouns like tu (you) because the verb ending already tells us who is doing the action. Since capisci can only mean "you understand," adding tu before it isn't necessary unless you want to sound very emphatic.