l'on

In French, the use of "l'on" instead of just "on" is mainly for euphony (to make the sentence sound smoother and avoid awkward sounds). 

It is often used after words ending in a vowel sound, such as "et," "si," "que," "où," etc.

For example:

• "Que l'on puisse comprendre" (instead of "Que on puisse comprendre") – sounds more fluid.
• "Si l'on veut réussir" (instead of "Si on veut réussir") – avoids the awkward "si on."

However, in modern spoken French, people usually just say "on" instead of "l'on." It’s more common in formal writing or literature.

"Si l'on" → A formal or neutral way of saying "if one" (it’s a general pronoun, similar to "you" in English when speaking in a general sense).