FiniteField
FiniteField[p,d] gives a finite field with pd elements.
FiniteField[p,f] gives the finite field p[α]/〈f(α)〉, where f(α) is an irreducible polynomial in p[α].
FiniteField[p,…,rep] uses field element representation rep, either "Polynomial" or "Exponential".
Please visit the official Wolfram Language Reference for more details and examples on core symbols.