Learn Italian: Anna guarda il quadro. - Anna looks at the painting.

In English, we say "looks at", which uses a preposition. But the Italian verb guardare already means "to look at" (or "to watch"). You don't need to add an extra word for "at". Anna just looks the painting: Anna guarda il quadro.

How do we get guarda from the dictionary verb guardare?

Guardare is a regular verb ending in -are. To make it match Anna (which is "she", or the third-person singular), we drop the -are ending and add -a. So, the base of the verb guard- gets an -a at the end, becoming guarda.

Why does this sentence use il instead of lo for "the"?

Quadro is a masculine, singular noun, so it needs a masculine, singular word for "the". We use il for most masculine words starting with a consonant. The word lo is only used for masculine words starting with specific sounds, like a z or an s followed by another consonant. Since quadro starts with a q, il is the right choice!