What does the slope and y-intercept mean?

The Y axis is the vertical line on a graph. This means that it is the one going up and down, the X axis is the line going left and right. More specifically the intercept is the point where a line on the graph meets or hits the X or Y axis. The slope is the angle of a line on a graph. Like a slide at a part might have a slope of 2/1 (2 over 1) meaning that it goes 2 points on the X axis every time it goes 1 point on the Y axis. That would be pointing up and to the right.

For example- if the equation is written as
y = mx + b
the slope is the number that is multiplied on the x, and "b" is the y-intercept, where the line crosses the y-axis