Elison in French is removing a final vowel that becomes silent in front of a word starting with a vowel elision happens because sometimes in French when a word ends in a vowel and the next word starts with a vowel it’s awkward to pronounce. When a vowel has become silent it’s marked in the written form by an apostrophe (‘)
Example:
Église
L'église
Je aime
J’aime
Ce est
C’est
Je ne ai pas
Je n’ai pas
NOTE: The elision also happens when the word begins with H muet because the H muet does not have sound
Le home
L’home