Refers to the everyday language or dialect spoken in a particular region, often contrasted with standard Japanese.
My grandmother speaks in the local dialect, so it's a bit difficult for her city grandchildren.
The vernacular of this area has many unique expressions.
方言 is the standard term for 'dialect' and is more common in academic or formal contexts. 土地言葉 is a more colloquial, everyday word for the local speech of a region.
Compound of 土地 (tochi, 'land, region') and 言葉 (kotoba, 'word, language'). The reading とちことば follows standard rendaku voicing of ことば.