assuming this is about a male
usually mean the opposite of "head in the clouds"

sometimes might be used to mean someone from the countryside/farming background, does context indicate this? If so you could use something like "a real country boy" or "a real farmer's son" or similar

Will take a try at this --

Since Swe has the idiom 'med fötterna på jorden', which was not used here, I suggest a stronger idiomatic phrasing than 'on the ground'. I am familiar with 'feet planted firmly on the ground' as the Eng idiom, but suggest using 'rooted in the soil' (I prefer in quotation marks, but ...) for emphasis, as it seems the Swe original is doing using 'i myllan' rather than 'på jorden'.