Learn Spanish (Latin America): El mutante le da un golpazo al guardia. - The mutant gives the guard a massive blow.

The suffix -azo is an augmentative, meaning it makes the original noun bigger, stronger, or more intense. Here, it is added to golpe (a blow or hit). The final e is dropped to add -azo, creating golpazo, which means a massive blow or a hard hit. While -azo sometimes means a strike done with a specific object (like puñetazo for a punch), here it simply intensifies the force of the hit itself.

Why is there a le before da if we already say al guardia at the end?

In Spanish, it is very common and often grammatically required to use an indirect object pronoun like le even when the actual receiver of the action (al guardia) is explicitly named in the same sentence. Think of it as pointing to the guard twice: The mutant to him gives a massive blow, to the guard.

Why is it al guardia (masculine) instead of a la guardia if the noun ends in -a?

Guardia is a word where the article determines the gender of the person. El guardia refers to a male guard. La guardia can refer to a female guard, but it is also used for a group or institution, like the police force or being on guard duty. Since the mutant is hitting a specific male guard, we use the masculine el, which combines with the preposition a to make al.