Linear

Linear means straight, as in not curved. A linear equation, when graphed, would be a straight, continuous line. The slope of a line is the rise/run, basically the y values divided by the x values. For example, if an equation was y = 5x, then the slope would be 5, since 5/1 is 5. The graph on the left (bottom) has a negative slope and the one on the right has a positive slope. 

In most graphs, the x axis is the independent variable (not changed) and the y axis the dependent variable.

To graph a linear equation, first get a set of random input values, use them in your equation to get some y values, and graph the dots. If you don't know how to graph dots, just find the x value of your dot, find the y value, and find a point where both the x and y values are the ones of your dot. The coordinate plane is explained here. Once you've graphed a set of dots, preferably 3 or more, draw a straight line through the dots, and you've graphed a linear equation!

There are three different ways to write a linear equation.

Slope Intercept Form: y = mx+b, where m is the slope and b is the y intercept.

Point-Slope Form: y-y(1) = m(x- x(1) ), where m is the slope and (x1, y1) is a point of the line.

Standard form: Ax+By=C, where A, B, and C are constants.

Some websites where you can practice this:

https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:forms-of-linear-equations/x2f8bb11595b61c86:summary-forms-of-two-variable-linear-equations/a/forms-of-linear-equations-review#:~:text=There%20are%20three%20major%20forms,%2C%20and%20slope%2Dintercept%20form.