It is about the following: I want to develop a tool where you click on a button "Browse", a Win Explorer window opens and there you can select a PDF file. After this is done, you click on "Compress now" and the file size is then automatically reduced so that you can send the PDF file, for example, via E-Mail (possibly also PDF files with images -> the quality of the images can also be degraded). Is there a way to implement such a tool with Python? If so how? Is there a specific module for it?
I have already started to program the tool so that now I can click on "Browse" and select a PDF file, now I have to go to the compressing part. Does anyone have any ideas?
Absolutelly YES.

To do that you will need a gui library as tkinter or PyQt5(there are more).
For manipulations of pdf like splitting or merging pdfminer or PyPDF2.
As for ziping there is a non-third party library like zipfile where you can zip files.
Then to make it a real app you can use cx_freeze or pyinstaller to make an exe!

Good Luck!!!
Compress select PDF-Files with Python - Reduce the Size