The end of the day for the map stats is defined in UTC. Internally, the stats are stored in Redis per day, being the day a "UTC day".
Each time the map is visualized it counts as a mapview. It doesn't require the map to be clicked, just the tiles to be requested to the server. If, for example, your map is embedded in an article in a newspaper site, when someone opens the article and the map is rendered in the browser that will count as a mapview. It doesn't require the user to go to the map and browse through it.
Another example: CartoDB public profiles usually feature the most popular map of the user, which is automatically embedded. Each time someone checks your public profile, it would sum a mapview to your featured map -- not the thumbnails of all the maps you might have created and published, just the featured map which is actually browseable.