and also what do 'runtime' means or environment

Legit questions, yes- but definitely OT for the Security forum.

Moving to the... um... where the devil does this fit?! Oh well- looks like mostly Win 95/98 stuff, so off we go...

The answer to your first question is something that you should be able to find as quickly as we could; as to the second:

A "runtime" environment basically refers to everything that is happening while a program/application is being executed (run). This is opposed to a "compile-time" environment, which refers to everything that is happening when a program is being compile from source code. Compiling from source is part of the process of the original creation of the program/application; it is the programming step that turns the bare program code (done in a programming language like C++) into a program which is executable (runable) by an end-user. A file with a .exe extention is an example of a compiled program.