32-bit Microsoft Word documents
When the transition to 64-bit operating system and software is complete, will i be able to open my old 32-bit Word documents or do they have to somehow be converted before?
The documents will be fine, 32bit only refers to the apps.
Macs and the macOS have been 64bit for about ten years.
you are posting in the High Sierra community if you a running any macOS from Mojave, High Sierra, Sierra and earlier
they will continue running 32bit apps. It is only with the introduction of the new macOS 10.15 Catalina that 32bit apps will no longer work. So if you are not going to upgrade then you are fine, you don't need to do anything.
If you are planning to upgrade to Catalina then you will need to check with the developers of your 32bit apps if there are 64bit versions or if there are plans for them to be updated. If you find your 32bit apps are not going to be updated and there is no suitable alternative then consider splitting your HD/SDD in to two partitions, one for High Sierra and one for Catalina you can then boot to High Sierra when you need to use your 32bit apps, you can do this in System Preferences> Startup Disk.