Venezia: due delfini nuotano davanti a Piazza San Marco

Essere + CI = there is/are

In the sentence “Sul Canal Grande, il più importante canale della città, c’è troppo traffico”, “c’è” is a contraction of “ci è,” which means “there is” in English.
It is used to express the existence or presence of something in a specific location, in this case, the presence of traffic in the Grand Canal of Venice. 

“Ci” is a pronoun that means “there” and “è” is the third person singular present indicative of the verb “essere” (to be). So, “c’è” can be translated as “there is” or “there’s” in English.

C’è = there is
Ci sono = there are

Here are some examples:

• C’è una penna sulla scrivania. (There is a pen on the desk.)
• Ci sono molti studenti in classe. (There are many students in the classroom.)
• C’è un concerto stasera al teatro. (There is a concert tonight at the theater.)
• C’è un nuovo ristorante in centro. (There is a new restaurant downtown.)
• Ci sono molte bellezze naturali in Italia. (There are many natural beauties in Italy.)
• C’è una festa sabato sera, vieni anche tu? (There’s a party on Saturday night, are you coming too?)
• Ci sono molti musei a Firenze, quale vuoi visitare? (There are many museums in Florence, which one do you want to visit?)