AVL Rotations Abbreviations
Please skip that article at tutorialspoint. Instead, read this article at GeekforGeeks, which is much better. You may want to check my answer to another question.

The common abbreviations for Left rotation, Right rotation, Left-Right rotation, Right-Left rotation are L, R, LR and RL respectively, as expected. These rotations can be applied to all kinds of binary search trees. For example, they are applicable to red-black trees, too.

Please note that there is minor confusion about the terminologies. However, I would say that more than 9 out of 10 times, you will encounter the mainstream terminologies as explained in that GeekForGeeks article.

A common reference to rebalance AVL trees is the Wikipedia entry on AVL trees.