Answer:
between the words “friends” and “Vanessa”
Step-by-step explanation:
On Saturday, Steven played soccer with four of his friends: Vanessa, Thomas, Isabel, and Logan.
A colon is often placed right before a list. Since a list of Steven's friends that he's playing soccer with comes right after the word "friends," we can say that the colon should be placed between "friends" and "Vanessa."