You can edit multiple records simultaneously. To do this:
In the List View, select the records you want to edit and click on Edit.
A dialog will open notifying you how many records you will be editing.
Select the Field you want to update
Enter the new value for that Field
In some cases, there will be additional options. For example, for List Fields, you need to choose if the new values will replace or be added to existing values.
Save and the records will be updated.