I'm not 100% sure since there isn't more context, but it seems like you're starting to talk about functions and graphing them. The main idea behind a function is that you can replace a variable with a number to find what the equation is equal to at that specific point. When it comes to a graph, usually you have an x axis, which is the horizontal axis, and a y axis, which is the vertical axis. If you pick 2 values of x and just replace them in the equation, you can find what y is equal to and place them on the graph. For example, if an equation is y=x+3, you can replace x with 0 to find what y is at 0, which is 3. You can do this again for x=1, which would give you a value of y=4. Because this is a linear equation, you can connect those 2 points and draw a line all the way across, and based on that line you can look at the graph and find a y value for any value of x.
Is this at all similar to what youre doing? Was there any part that was confusing or specific questions about another part of it?