Let suppose you want to update product category for products, from product list view, filter the items you want to update their product category:

and than press on Select checkbox in the header:

this will select all items in the first page (in case you have multi page), once you checked the select checkbox, click on product category in the first record:

and change it, then a confirmation message will be shown  and ask you if you want to update all selected records.

Then you will see everything updated at once: