You will need:
Note that the C code uses C++ style comments (//....) in a few places. The C language standard, ISO 9899:1999, commonly known as "C99" added a requirement that compilers support this style of comment, which was already a common extension, though very old C compilers may not recognise it or need special tweaks.
Also very useful:
/bin/sh
Note that they are not essential. If you are using Microsoft VisualStudio, it can build everything automatically but otherwise it is exceedingly tedious to build without these facilities since you must build everything manually. The document Prosody installation guide: building without using the Makefiles describes how to do this.
The version required of perl is version 5, but since this was released in 1994, it would be surprising to find a system still using perl 4.
If you have all of these you are now ready to start the first-time build.
If you want to use an automated build system other than GNU make (such as a visual integrated development environment), you should read Prosody installation guide: building without using the Makefiles, which tells you what compiler options you need, and Prosody: layout of the distribution which should help you determine where to find the information on what files are used when building each part of the distribution.
A comprehensive set of GNU tools for Windows is available from http://cygwin.com including gcc, make, and bash. Note that several of the scripts in the Prosody distribution assume that /bin/sh is a shell. Cygwin does not do this by default. You can easily fix this with:
mkdir /bin (in case it's not already there) cp `type -p bash`.exe /bin/sh.exe