to have more money than you had in the past or more money than most other people

Obviously we're better off now that we're both working. 现在我俩都工作，经济状况显然比以前好了。

When his parents died, he found himself $100,000 better off (= he had $100,000 more than before). 父母死后，他发现自己一下子多了10万美元的财产。

people who have more money than most others

The new tax will not have a serious impact on the better off. 新征收的税对经济宽裕的人影响不会很大。