A polynomial is a mathematical expression containing a sum of powers in one or more variables multiplied by coefficients or we can say an expression of more than two algebraic terms that contain different powers of the same variable.
But;
• Not divisible by a variable.
• A variable's exponents can only be 0,1,2,3,... etc.
• It can't have an infinite number of terms.

Example - 5xy² – 3x + 5y³ – 3

And a polynomial with real coefficients is a product of irreducible polynomials of first and second degrees or in simple words, a polynomial having only real numbers as coefficients is the real coefficient Polynomial.