If something happens less and less, it becomes gradually smaller in amount or happens less often.

He's less and less able to look after himself. 他越来越不会照顾自己了。

As their family grew, she had less and less time to write.

Americans do less and less of their shopping in malls these days.

Gradually, I started to depend less and less on other people to help me.

Employees started to travel less and less with each passing month.

See also: less determiner pronoun adverb