Answer
Center at $\quad(0,0).$
Vertices at $\quad (-2,0),(2,0),(0,-2),(0,2)$
Focus at $\quad(0,0).$
Work Step by Step
Divide the equation with $4$ ... (we want the standard form)
$\displaystyle \frac{x^{2}}{4}+\frac{y^{2}}{4}=1$
$\displaystyle \frac{x^{2}}{2^{2}}+\frac{y^{2}}{2^{2}}=1 \quad $...$a=b=2,$ a circle, radius $=2$.
(both axes are main axes)
Center is at $(0,0)$.
The focus of the ellipse is at its center, $(0,0)$.
The vertices are $(-2,0),(2,0),(0,-2),(0,2)$