A monomial is a mathematical expression that has only one term. It can be a number, a variable, or a combination of a number and a variable raised to a power. For example, 5, x, and x^2 are all monomials.

Think of it like building with blocks. A monomial is like a single block. You can have a block with a number on it, like 5, a block with a letter on it, like x, or a block with a number and a letter on it, like x^2. Each of these blocks is a monomial because it is a single piece.

In math, we use monomials to build more complicated expressions. For example, if you have two monomials, like "5x" and "3x", you can combine them to make a new expression, "5x + 3x", which has two terms.

So, a monomial is a mathematical expression that has only one term. It can be a number, a variable, or a combination of a number and a variable raised to a power. It's like a single block that you can use to build more complicated expressions.