Student or Learner
I am not sure when to use "The" and when to use "a", so can you please help me out.
Not a teacher.
From my understanding, you use "the" when referring to something specific and you use "a" when referring to something in general.
"The American speaks good English."
You are referring to a specific American that has a talent for English.
"An American speaks good English."
"A" turns into "An" when the next word starts with a vowel or a vowel sound. The sentence means that you are referring to some random American who can speak well, not a specific one.
"The dog is barking."
This could be said if someone is annoyed at the dog next door. You know the dog that you are talking about.
"A dog is barking."
You hear a dog barking somewhere in your neighborhood, but you don't know which one it is.