to put it (simply|mildly|briefly)

简单地说, 简而言之

used to introduce a simplified version of a statement

To put it simply, the project was a complete success.
简单来说, 这个项目完全成功了。
To put it mildly, the weather yesterday was terrible—it was pouring rain all day.
简单来说, 昨天的天气糟透了—下了一整天的雨。
To put it briefly, the company's financial situation is precarious, and we need to take action immediately.
简而言之，公司的财务状况不稳定，我们需要立即采取行动。
To put it simply, she's the most qualified candidate for the job.
简单来说, 她是这份工作最有资格的候选人。
To put it mildly, the traffic during rush hour is horrendous.
简单地说，高峰时段的交通状况非常糟糕。