now, coming from the right, notice the line, it it hits (6,8) and keeps on going down and down and down to (5,7) and so forth, as it goes towards 2 from the right, is 5, then 4.99, then 4.89, then 4.8 then 4.5, and 4.2 and so forth.
ooops, there's a hole at y = 4, so, that simply means it will never hit 4 in proper, it'll be 4.1, 4.00001, 4.0000000000000000000001 and so on, so, it seems to be approaching 4, thus the limit is 4.
recall that, a limit is simply "what is approaching", not what it is at that point, in this case, it will never reach 4, BUT is approaching it, and therefore the limit from the right is 4.