What is the meaning of point (7.5, 12)?

It is in form (x,y) (ususally)
7.5 and 12
there is something called a coordinate system where a line called the y axis runs vertically for infinity and a line perpendicular to it, crosses it. the other line is called the x axis which also extends for infinity
the point where they cross is point (0,0) or the origin
basically the numbers tell you how far you are from the axises
on the y axis, + numbers are up and - numbers are down
on the x axis, + numbers are to the right and - numbers are to the left

7.5=x and 12=y
+7.5 is positive
7.5 means that the point is 7.5 units to the right of the origin in relation to the x axis

12 is positive
12 means that the point is 12 units up from the origin in relation to the y axis

hope this helped. feel free to ask if its too confusing