This is an equation of a line.
We can rewrite it in point-slope form:
-2x = -1 - y
We can then graph this line by plugging in 2 points then connecting the two points.
Two points that work are:
(0, -1) and (2, 3)
You can then connect those two points on a graph and all the points on the line are solutions.
I hope this helped,