Learn Italian: Bisogna essere prudenti quando c'è traffico. - One must be cautious when there is traffic.

Bisogna means "it is necessary" or "one must." It is an impersonal expression, meaning it doesn't take a specific subject like "I" or "you." It is always followed directly by an infinitive verb, which is why we use essere (to be) right after it.

Why is prudenti plural if the English translation uses the singular "one"?

This is a special rule in Italian! When you use an impersonal expression (like "one must") with the verb essere (to be), the adjective that describes it must be in the masculine plural form. That is why we use prudenti instead of the singular prudente.

What exactly is c'è?

C'è means "there is." It is made by combining the word ci (there) and è (is). Because è starts with a vowel, the "i" in ci is dropped and replaced with an apostrophe to make it flow better when speaking.

Why is there no article before traffico?

Just like in English, Italian often leaves out the article "the" when talking about an uncountable noun in a general way. We say "when there is traffic," not "the traffic," so Italian just uses c'è traffico.