Visual Basic (VB) is a unique computer language---at least it was when it first came out. Now there are many imitators. VB allows you to quickly and easily develop a bank of visual controls with sliders, switches and meters or a complex form for a user to fill out. It uses the BASIC language which is known to most computer programmers, and which can be learned quickly if it is not already known.
VB is a Graphical User Interface (GUI) language. This means that a VB program will always show something on the screen that the user can interact with (usually via mouse and keyboard) to get a job done. The first step in building the VB program is to get the GUI items on the screen. This is done via pull-down menus that list the available graphical objects. Every system is slightly different (Mac differs from Windows and VB4 Differs from VB6) but, generally speaking, left-clicking on an object allows you to describe attributes like size and position. Right clicking allows you to write code. For example, if the GUI item is a switch, left-clicking would allow the programmer to say how big the switch was, how it was labeled and where on the screen it is positioned. Right-clicking on the switch would bring up a window that allows the programmer to write the code that describes what happens when the user clicks the switch.
It is considered good programming practice to modularize your programs. Instead of thinking of a computer program as a single large collection of code, the good programmer writes code so that you never need to look at more code than fits on the screen (or page) at one time. If you program in modules like this, the program is easier to understand and easy to update. Updating will likely be done by someone else so it is import that the program be easy to understand. Small (page size) modules where it is clearly indicated what comes into the module and what goes out makes a program easy to understand. VB forces you to program in a modular fashion because each GUI item contains part of the code---the part that applies to that GUI item.
Object Oriented Programming (OOP) is a concept where the programmer thinks of the program in "objects" (however abstract the objects may be) that interact with each other. In OOP, all the code associated with that object is in one place. Once again, VB forces this good programming practice. The GUI items are the objects and all the code associated with the object are just a click away. This natural way of enforcing good programming practices---plus the ease of programming in BASIC---is exactly why VB has found so many devoted fans.