"A" phrases with "gustar"
When using “gustar” or verbs like it (those that require an indirect object pronoun), you’ll often see the prepositional phrase with “a” like “a mí,” “a ti,” “a él/ella,” etc.
This prepositional phrase serves two purposes. It can either add emphasis or it can clarify. Take a sentence like “A mí me gustan las fresas” (“I like strawberries.”) as an example. You could remove “a mí” and the sentence would still have the same meaning. Including the prepositional phrase, though, just adds a bit more emphasis that the speaker, specifically, likes strawberries.
Now let’s take a sentence like “A mi hermana le gusta el café” (“My sister likes coffee”) as an example. Again, you can remove “a mi hermana” and the sentence would be grammatically correct. The indirect object pronoun “le,” though, can mean “to/for him,” “to/for her,” or “to/for you (formal).” Without some more information, “Le gusta el café” is a very ambiguous statement. Who likes coffee? Adding “a mi hermana,” though, removes any doubt.
This structure may take some getting used to, but practice makes perfect!