To Bulk print multiple invoices on web, please follow the below mentioned steps,
Step 1 - Kindly click on sales >> Click on invoices >> Click on actions >> Click on bulk actions
Step 2 - Please select the invoices which you want to print >> Click on print.
Note - You can only print 50 invoices at a time with the help of bulk actions.
Step 3 - After clicking on print you will get a pop up that are you sure want to print selected documents >> Click on print to print the documents.