Answer :
If you already have an equation, all you have to do is locate the slope and look after it. But if it's in a graph, it's where the line is crossing the y-axis.
An example of the equation would be
y=2x+3
y=mx+b
2 would be m which is slope
and 3 would be b which is the y-intercept
An example of the equation would be
y=2x+3
y=mx+b
2 would be m which is slope
and 3 would be b which is the y-intercept