La puzza è forte.

Puzza is a feminine singular noun, so it normally takes the feminine singular definite article la when you mean the stink / the smell.

So:

• la puzza = the stink / the bad smell
• una puzza = a stink / a bad smell

In a normal full sentence like this, leaving out the article would usually sound unnatural.

Puzza usually means a bad smell. It has a negative sense, like stink, stench, or bad odor.

If you want a more neutral word for smell, Italian often uses odore:

• L’odore è forte. = The smell is strong.
• La puzza è forte. = The stink is strong.

So puzza is stronger and more unpleasant than odore.

È is the he/she/it is form of essere (to be).

The accent matters because:

• è = is
• e = and

So:

• La puzza è forte. = The stink is strong.
• La puzza e forte would be incorrect.

Some Italian adjectives have the same form for masculine and feminine singular. Forte is one of them.

So you get:

• il rumore forte = the loud/strong noise
• la puzza forte = the strong stink

In the plural, it becomes forti for both masculine and feminine:

• i rumori forti
• le puzze forti

So forte is correct with puzza, even though puzza is feminine.

Here, forte means strong.

Italian forte can mean different things depending on context:

• un uomo forte = a strong man
• una musica forte = loud music
• un odore forte / una puzza forte = a strong smell / strong stink

So in this sentence, it refers to intensity, not volume.

It is pronounced roughly POOT-tsa.

A few useful points:

• u sounds like oo in food
• zz is pronounced like a strong ts sound here
• the double consonant matters, so say it a bit more sharply than a single z

So puzza is approximately POOT-tsa, with stress on the first syllable.

This is the normal word order in Italian: subject + verb + adjective/complement.

So:

• La puzza = subject
• è = verb
• forte = adjective

This matches English fairly closely: The stink is strong.

Italian can sometimes change word order for emphasis, but La puzza è forte is the standard, neutral order.

Yes. That means The stink is very strong.

Molto is a very common way to intensify an adjective:

• La puzza è forte. = The stink is strong.
• La puzza è molto forte. = The stink is very strong.

That is a completely natural variation.

Yes, very naturally, especially when talking about an unpleasant smell.

For example:

• Che puzza! = What a stink!
• C’è puzza di fumo. = There’s a smell of smoke / It smells like smoke.
• La puzza è forte. = The stink is strong.

So this is normal everyday vocabulary, not an especially formal word.

They are related, but not identical.

• La puzza è forte = you are talking about the smell itself and saying it is strong
• C’è puzza = There is a bad smell / It stinks

So C’è puzza is often used to say that a bad smell is present, while La puzza è forte describes how intense it is.