high
The word 'alto' refers to something that is at a great vertical extent in Italian. It can be used to describe things like a 'high mountain' ('monte alto') or 'high heels' ('tacchi alti'). Also, it can be used in a metaphorical context, such as 'high price' ('prezzo alto').
The tree is very tall.
In this sentence, 'alto' is used to describe the height of the tree. It is an adjective in this context, placed after the noun it modifies, which is a common structure in Italian.
The volume is too loud.
In this example, 'alto' describes the level of the volume. Although 'alto' literally translates to 'tall' in English, it can also be used to mean 'high' or 'loud' when referring to sound levels.
I live on the high fourth floor.
In this sentence, 'alto' refers to the height of the fourth floor. It is common in Italian to describe floors or levels of a building as 'high' (alto) or 'low' (basso).