What is meant by a "two-lane" road?

Solution 1:

Two-lane expressway (same concept as road) :

• A two-lane expressway or two-lane freeway is an expressway or freeway with only one lane in each direction, and usually no median barrier.

Two-lane expressway:

Two-lane road:

Wikipedia

Your second picture represents a:

multilane road/highway:

• (of roads and highways) having two or more lanes for traffic

Solution 2:

According to the World Road Association-PIARC, an international standards body, a two-lane road is simply a

Road designed to permit two lanes of traffic to be accommodated side by side.

A search on the term shows that this usage is used by governments and construction companies in the United States, Canada, New Zealand, and Scotland. We may presume that at least in industry circles, the understanding of a two-lane road would be something like what the Manual on Uniform Traffic Control Devices, which sets US national standards for road signs and markings, offers in this diagram:

Roads with more than two lanes, regardless of direction of traffic, are referred to generically as multi-lane roadways.

However, lanes should not be confused with carriageways or with directions of travel. Consider, for instance, this Wikimedia image of highway 401 in Ontario:

There are sixteen to seventeen lanes of traffic, but these are divided up into six carriageways, three in each direction. So the confusion that a four-lane road refers to a road with four lanes in one direction may arise because it is hard to imagine such a large road on a single carriageway; almost certainly it would be at least a dual carriageway, with four lanes of traffic in each direction, but properly an eight-lane roadway.

Solution 3:

A two lane road means one lane in each direction. Otherwise, there would be no need for special instructions, like this one, teaching drivers how to safely pass on a two lane road.