If it's a placeholder for singing:
* La la la: This is the most common way to represent singing in French.
* Lalala: This is also acceptable, as it's a common sound in many languages.
If it's used as an expression of nonsensical speech:
* Blah blah blah: This is similar to "lalala" and conveys a lack of meaning.
* Des bêtises: This means "nonsense" and can be used to describe meaningless talk.
* Des paroles en l'air: This translates to "words in the air" and implies empty or meaningless talk.
If it's a sound effect:
* La la la: This is the most appropriate way to represent the sound.
* Un son d'oiseau: This means "a bird sound" and can be used if the "lalala" sound is similar to bird song.
Ultimately, the best translation depends on the specific context in which you want to use "lalala."