The way PortablE works is that it takes your E code, and generates C++ code, which is then USUALLY given to GCC to create an executable.
But PortablE does something very unusual when generating the C++ code: It preserves the comments & indentation (etc) present in the original E code (as far as possible). This means that it is normally possible for a human to read the generated C++ code, and find it not too much harder to understand than the original E code.
(So potentially you could use PortablE to convert an E program to C++, or maybe use E code as part of a C/C++ program (although that would be more difficult), or perhaps show your E program to someone only familiar with C/C++, or some other use I haven't thought of!)
There WAS one big exception to this though: MUI code. Because traditionally AmigaE (and thus PortablE) used MUI macros which worked quite differently to those you use with normal C code, as it used a feature that C does not have. Which for PortablE meant the generated C++ code was quite different to normal C code (and in fact pretty unreadable).
What I have now done is add a feature to PortablE (which AmigaE did not have), which allows it's MUI macros to work the same way as they do in C code. And the end-result is that the generated C++ code looks very similar to what you'd see in normal C code. So now PortablE generates human-readable C++ code for almost any E program you may throw at it, even if that program uses MUI