That means there are more enchantments added for you to use.

When you finish this process, you should see white symbols floating towards the book and table. Since Minecraft only checks for a maximum of 15 nearby bookshelves, there is no reason to put more bookshelves. Carpet or torches laid on the floor between the table and bookshelves will block the bookshelf bonus from reaching the enchantment table. After placing the enchantment table, bookshelves should be put 1 block away from all sides of the enchantment table (leaving a block of air on all sides). Up to 15 bookshelves may be put around the table to allow higher-level enchantments. First, set up the enchanting area. As of 1.8 The Bountiful Update, lapis lazuli is needed too.

To enchant, you need an enchantment table, several experience points, and an item you wish to enchant. 15 bookshelves achieve the maximum level of enchantments. This process is very useful, If books are within a close range of an enchantment table, higher-level enchantments and more enchantments can be applied to a tool. However, this can only be done with an anvil and/or enchanted book. Using the enchantment table method lets the player enchant armor, shovels, pickaxes, axes, swords, and bows. Much more stuff can be enchanted. An enchanted item will display any current enchantments and their level of strength on the item (unless the enchantment is limited to level 1. When armor or a tool is enchanted, it will shine (much like a potion) with an animated purple effect, letting the holder and any nearby players see the item is enchanted.

Can you get silk touch from fishing