When $x=0$, you are on the $y$-axis. Read the $y$-value where the curve meets that axis.

Use the tick marks to make sure you read the correct integer value.

In Desmos, create a table and enter three clear points from the graph, such as $(-1,0)$, $(3,0)$, and $(1,-4)$.

Type y1 ~ a x1^2 + b x1 + c to perform a quadratic regression based on the table.

Use the regression equation Desmos gives to find the output when $x=0$ (substitute $x=0$ into the model) to obtain $f(0)$.

Since $f(0)$ is the output when $x=0$, it is the $y$-coordinate of the point on the graph where $x=0$ (the $y$-intercept).

On the graph, when $x=0$, the parabola passes through the point $(0,-3)$. Therefore, the value of the function at $x=0$ is $-3$.