The Zutilo add-on provides some batch editing functions. If you want to try using them, install Zutilo. Then go to "Tools" -> "Zutilo Preferences…" -> "User Interface". Add the "Copy item fields", "Paste into empty item fields", "Paste non-empty item fields", "Paste all item fields", and "Paste item type" functions to the Zotero or Zutilo context menu.

Example: I forgot to indicate the editor in several individual essays of a book. Is it possible to add the information of the essays at the same time or do I have to do it individually?

This could be achieved in the following way:
1. Create a new (dummy) empty book section item.
2. Enter the editor information.
3. Select the new item, right-click it and select "Copy item fields".
4. Select the items you want to edit and use "Paste into empty item fields".
5. The editor information will be appended to the selected items.

(An alternative could be to select an existing book section item with the correct editor information. Right-click it and select "Duplicate Item". Remove the information that you don't want to add to the other items, e.g., the author. Use "Copy item fields" on the edited duplicate, then use "Paste into empty item fields" as in step 4.)

See this discussion for more details:
https://forums.zotero.org/discussion/85593/editing-multiple-items-at-once