Where (What provinceĐ is this place?
The sign reminds me of old terracotta (medicine/herb) pots (หม้อต้มยา) I used to see back in my roaming days. It'd be a pity that we abandoned this cultural practice in favour of modern (western/synthetic chemical) medicine.
By the way if you have time and a chance to go to Korat, I would recommend going to 2 techno-cultural exhibits at Suranari University of Technology (SUT - มหาวิทยาลัยเทคโนโลยีสุรนารี มทส). One is about old Thai techonlogies, another on old Thai ways of life. Both are next to each other. Both are really good sources of imagination ;-) A few hours will be needed. The food at the Uni canteen ain't that bad either.
PS. You may have to insist that you want to see these - many people don't know they exist even people at the uni. If you have problems, try asking where Dr Twich Jitsomboon's collection is. ;-)