The y-intercept is kinda like how far the slope is from zero, but it can only be applied to the y-axis.
The slope is... well... the slope-- like how steep it is. If a slope is 2/1, like in the graph, it will go higher 2 units every 1 unit across. Or, if the slope is 1/4: The slope will go 1 unit higher every 4 units