Does anyone know what it means? It's not the XP remaining.
Best Answer
That number is the total amount of trainer experience you've earned. So, in the image attached in the question, that trainer has earned 72,238 XP at the current trainer level, needs 100,000 XP to reach the next trainer level, and has accumulated 407,238 XP across all levels in total so far.
Note: As of Pokemon GO version 0.29.1 or so, the "footprint" indicator was disabled, and all Pokemon are three footprints away. This is a known bug, and the fault of Niantic Labs (and the server overload as a result of the game's popularity.
Note 2: As of Pokemon GO Version 0.30.1, the Footstep indicators have been removed. The game will show all Pokemon within 200 meters of your current location, with the nearest being anywhere in the list.
Each footprint represents 50 meters of distance, starting with zero footprints means the Pokemon is no more than 50 meters away.
For example, one footprint means the Pokemon can be 51-100 meters away in any direction. Three footprints means the Pokemon is at most 200 meters away.
Note, however, that these numbers do not reflect Pokemon spawned through Incense or Lure Modules. Additionally, there is (at the time of writing - version 0.29.0) a bug that causes the distances to not update properly, causing the approximate values to be slightly "off."
The bar above a Pokemon represents their CP in a relative range, for that specific species.
The lower end of this bar represents some (still unknown) minimum value for a single species. The higher end of this bar represents the maximum CP this Pokemon can have at your current Trainer level.
For example, Rattatas are rather weak, therefore their CP range is a lot smaller than that of a Drowzee, which explains the bar difference you are seeing.
You may fill the bar up by training your Pokemon. Note that absolutely nothing happens to the Pokemon when you fill the bar -- you've just reached the Pokemon's current CP cap.
Best Answer
That number is the total amount of trainer experience you've earned. So, in the image attached in the question, that trainer has earned 72,238 XP at the current trainer level, needs 100,000 XP to reach the next trainer level, and has accumulated 407,238 XP across all levels in total so far.