Hello Ezekiel !
LE is a type of personal pronoun that fulfills the function of indirect complement ( in this case, it's the 3rd person pronoun, singular ) For example: " Se le rompió la computadora" = " ( a él ) se le rompió la computadora" ( is similar to say "to him" )
Other example: " Cuánto le debo por las naranjas?" = " Cuánto LE debo ( a Usted) por las naranjas?" = How much do I owe you for the oranges ?
There are personal pronouns that function as direct and indirect complements.
Direct Complement: 1ª person = ME (singular) / NOS (plural) // 2ª person = TE (singular) / OS (plural) // 3º person = LO, LA (singular) / LOS, LAS (plural)
Indirect Complement: 1ª person = ME (singular) / NOS (plural) // 2º person = TE (singular) / OS (plural) // 3ª person = LE, SE (singular) / LES, SE (plural)
Other examples: "Ayer TE envié una carta" in this case, TE indicates that I sent TO YOU a letter ( TE envié A TI una carta, it's an Indirect Complement) / "Pero no LA recibiste " ( LA refers to the letter, you don't received the letter, it's a Direct Complement)
This type of pronouns can sometimes be attached to the verb: "PásaME la sal" in this case, ME means TO ME. But if I say: "PásameLA" I'm talking about the salt, LA referes to the salt.
"A" is a preposition, one of the more used and had several applications. It can be combined with articles and indicates the term, object or direction of the action.
I cannot explain all the uses of this preposition, but I'm going to give you examples with AL.
If I say " El gato persiguió AL ratón " (the cat chased to the mouse) in this sentence, AL is the contraction of A and EL ( el gato persiguió a el ratón )
But if AL is followed by an infinitive: "AL finalizar el examen, salimos felices" express concurrency ( when we finished the test, we left happy )
I hope that my explanation has been clear. Please, let me know if you have any doubt, I will try to improve my response.