Learn French: La pomme est là. - The apple is there.

Pomme is a feminine noun, which means it must use feminine articles. To say "the apple" like in this sentence, you use la pomme. If you wanted to say "an apple", you would use the feminine indefinite article: une pomme.

What is the difference between La at the beginning and là at the end?

The accent mark changes the meaning entirely! La (no accent) is the feminine word for "the". Là (with a grave accent) means "there" or "here". They sound exactly the same, but the accent tells you which one is which when you read.

If I want to say "An apple is there", how does the sentence change?

You would swap the definite article (La, meaning "the") for the indefinite article (Une, meaning "a" or "an"). Because pomme is feminine, the sentence becomes: Une pomme est là.

Why do we use est here?

Est translates to "is". It is a form of the very common verb être (to be). You use it whenever you are talking about a singular third person or thing, like "he", "she", or "it". Here, the apple (it) is there.