The slope-intercept form of a line is
[tex]y=mx+q[/tex]
where m is the slope and q is the y-intercept. Let's rewrite the equation of the line to match that pattern:
[tex]-3x+4y=-12 \iff 4y = 3x-12 \iff y = \dfrac{3}{4}x-3[/tex]
The y intercept tells us that the line passes through the point [tex](0,-3)[/tex]
The slope tells us that every time x increases by 1, y increases by 3/4. This is equivalent to say that every time x increases by 4, y increases by 3 (and it's easier to draw).
So, you can start from point [tex](0,-3)[/tex], and then increase x by 4 and y by 3 to find the next point, which is [tex](4,0)[/tex].
Connect the two points, and you'll have the line.