Rd. is the short written form of Road, and you almost only meet it in addresses. On an envelope, a name card, a map, or an English street sign, the street name comes first and Rd. comes after it: Hill Rd., Nanjing E. Rd. It tells you the official label of that street is Road, not Street or Lane — though actually those labels do not change how the place feels. A quiet Rd. and a busy St. can look the same; the letters are just part of the name. British writing likes the full stop (Rd.). American writing often keeps it too, but you will also see Rd with no stop. Nobody says “Rd” when they talk, except when they are reading a written line out letter by letter. You say road. If you are filling in an English form, copy the Latin-letter form from the sign or the building; do not write Rd. for a street that is officially a Street, a Lane, or a Section.