Answer
$f(0)$ is equal to $0$.
Work Step by Step
Note from the graph, at $x=0$ there is open circle for $y=3$ and closed circle for $y=0$.
It means, $y=3$ is not included and $y=0$ is included.
So, $f(0)$ is equal to $0$.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.