Divisibility in ring theory is like sharing toys with your friends. Let's say you have a bunch of toys and you want to share them with your friends. If you have 10 toys and you have 2 friends, you can give 5 toys to each friend. This means that 10 is divisible by 2.
In the same way, in ring theory, we have something called a ring which is like a collection of numbers or objects. We can also have an element in the ring, which is like one of your toys.
Now, let's say you have an element a in the ring and another element b in the ring. If we can find a way to divide a by b and get a whole number, then we say that a is divisible by b. This means that we can share a in equal parts with b.
For example, let's say we have the ring of integers, which is the collection of all positive and negative whole numbers. If we take the element a=12 and the element b=3, we can divide 12 by 3 and get a whole number 4. This means that 12 is divisible by 3.
However, if we take the element a=5 and the element b=3, we cannot divide 5 by 3 and get a whole number. This means that 5 is not divisible by 3.
So, in summary, divisibility in ring theory is like sharing toys with your friends - if we can divide one element by another and get a whole number, then the first element is divisible by the second element.