ground floor level

基本解释

At the ground floor level, you can see across the space from the entrance court to the bedroom.
首层开阔通畅，可以从入口一直看到卧室。
julemei.com
The building is open on all four sides at ground floor level, revealing a series of social areas that include a cafe, an events space, a lounge and a games room.
一层（译者注：即国内所说的二层）还包括一个会堂，而小办公室和会议室则在第三、第四层可以找到。
Large glass doors and operable windows at ground floor level ensure that each dwelling offers abundant light and ventilation, while making certain that the building remains secure and private.
首层的大玻璃门和可开闭的窗户确保了住宅充足的光照和通风，同时还保证了安全性和隐私性。

For small investors it will be either a great level-the-playing-field opportunity to get in on the ground floor of promising startups or a federally sanctioned invitation to fraud on a scale not seen since the boiler-room days.
FORBES: What You Need To Know To Profit From Crowdfunding