This is a US Road Name sign found at road junctions everywhere in the USA (virtually no person living in the US that travels the road has not seen one of these! ;-)). This is the upper sign with the post. The lower sign without the post (KUID:254080:23020) is placed seperately.
The road name on the sign can be changed in Surveyor by clicking the question-mark button in the Objects menu. The sign will then show a yellow asterisk above it, so click the sign, type in your text and choose the tick to apply it. (Tip: Generally you will want to suffix your road name with a standard suffix such as RD, DR, etc. See screenshot for an example.)
When installed it will be found under USA -> Residential.