Ols is a method that consists of solving the last pair of f2l at the same time solving the oll, but unfortunately this method has many algorithms which makes it difficult to learn this method. But in this video I showed easy cases of ols, in which all the pieces of the oll are oriented and just need to insert a pair of f2l. These cases are very tricky because you think that after inserting the pair you will have an oll skip, but no.