this is a help question and should be in [VB Help], not [VB Submissions]. but since you're new, I'm going to let it slide this time... though this post will be moved later on.
Procedure is basically a block of code. There're different types.
A sub procedure is a custom block of code. It could be a set of steps that are often repeated. Having them in a procedure will allow you to reuse the code. Such as clearing all the fields for example, or updating some values.
A function procedure is a one used to calculate and return a value. It is just like a math function - you plug in the numbers and it spits out the answer.
A event procedure is the one that handles events such as button click. It is the set of steps that happen when a certain even in the program occurs.