This is the 2259th most frequent Japanese word.
足し
"足し" means "addition" or "supplement."
In this context, 足し represents a value addition, signifying an enhancement or improvement in life.
友達を作るのは人生の足しになる。
Making friends adds value to one's life.
In this sentence, 足し refers to something that can serve as assistance or benefit to someone, implying addition or support.
彼の足しにはならないこともある。
It might not be to his advantage.
Here, 足し denotes the purpose to add or supplement something, enhancing or completing.