Answer:
I have uploaded a picture so you could understand it a little more.
A linear function is when there is a table that gives numbers that represent a function, as shown in the picture.
In the Image, there is a table with a x and y column. And in both columns, there are numbers.
This is what the table looks like in the picture:
<u>  x   y   </u>
 0    4                       The key is y = 2x + 4
 1     6 <------      lets grab the number 1 in the x column and lets 
 2    8       multiply it by two.  Now add four to it, and we will
 3    10                  have the number 6 in the y column.
 4    12
I hope I helped you! God bless :-)