x^2 - y^2 + z^2 = 4

We just started this topic, and I am really struggling with it. For this question, you are to use the traces x=0, y=k, z=0 and then identify what this surface is and draw it.

for x=0:
-y^2 + z^2 = 4
y^2 - z^2 = 4 I am not sure, is that a hyperbola?

for y=k:
 x^2+z^2=k^2+4 a circle I believe

and z=0:
x^2-y^2=4 Hyperbola also..?

If someone could assist me from here on how to identify this graph, I'm a little bit lost.