Learn Italian: Difficilmente lavoriamo il fine settimana.

To form an adverb, you usually add -mente to the feminine singular form of an adjective. However, the adjective difficile (difficult) ends in an "-e" for both masculine and feminine. For adjectives ending in "-e", you simply add -mente directly to the end of the word, giving us difficilmente.

Why is difficilmente translated as "hardly ever"? Shouldn't it mean "with difficulty"?

Literally, it does mean "with difficulty" or "difficultly". However, in everyday Italian, difficilmente is commonly used to express that something is highly unlikely to happen. In English, this naturally translates to "hardly", "barely", or "hardly ever".

Where is the word for "on" before il fine settimana?

Italian doesn't need a preposition here. Just like with days of the week, you only need the definite article to express that something happens regularly during that time. Using just il before fine settimana is enough to mean "on the weekend" or "on weekends".

The word fine (end) is usually feminine. Why does it use the masculine article il here?

It's true that "the end" by itself is the feminine la fine. However, when combined into the set phrase il fine settimana (the weekend), the entire compound noun is treated as masculine. You will also frequently hear Italians just say il weekend!