This is a plugin for Dolphin & Konqueror, which provides simple GUI actions to combine or alter PDF files. Dolphin & Konqueror are applicable to Linux only.
pdfForts does not appear to be packaged by many distributions. Obtain from https://github.com/sjau/pdfForts. It does require several dependencies, which typically are packaged by distributions - these will need to be installed via the package manager.
Note that the install.sh script appears to have been written for KDE4 and does not put files in the correct location for KFrameworks5. see http://www.makeuseof.com/tag/build-linux-productivity-machine-kde-service-menus/. All that is required is to copy files to correct locations:
*.sh to /usr/bin/pdfForts
*.desktop to /usr/share/kservices5/ServiceMenus/pdfForts
Following installation, open a new Dolphin window, select one or more PDF files and right-click to see what tasks are availbable from the "Actions" sub-menu.
Other Linux file managers, such as Thunar, also have facilities for service menus and pdfForts should be able to work there too.