Sensor level above ground?

When I add my sensor it asks what is the “level above ground”, is this the physical distance from the ground to it, or is it the altitude settings of where I am? Just want to make sure I’m not misunderstanding ground/sea level, etc.

It is writtten here, isn’t it ?

Please read attentively.

Sorry. I don’t know how I could of missed that. Thanks for your prompt response.