Learn Italian: Stavo toccando le belle sculture di marmo con le mani. - I was touching the beautiful marble sculptures with my hands.

Belle is the feminine plural form of bello. The current lesson focuses on how masculine forms of bello change a lot depending on the next word's starting letters (like bel, bei, begli). But the feminine forms are much easier! You just use belle for feminine plural nouns, regardless of whether the noun starts with a consonant or a vowel.

What tense is stavo toccando?

This is the past continuous tense, meaning "I was touching". You make it by combining the imperfect tense of stare (here, stavo for "I") and the gerund form of the verb toccare, which is toccando (touching). It is used to describe an ongoing, continuous action in the past.

Why does it say sculture di marmo instead of just putting marmo before the noun like in English?

In English, we often put a material right before a noun, like "marble sculptures". In Italian, you cannot stack nouns like that to act as adjectives. Instead, you use the preposition di (of) to describe the material something is made of, literally saying "sculptures of marble".

The translation says "my hands", but isn't le mani just "the hands"? And why does a feminine plural word end in -i?