Compared to ~40 in a chess game would be 2 min per side / 20 moves = 10 seconds a move. (http://www.chessgames.com/chessstats.html)
https://en.wikipedia.org/wiki/Byoyomi
After the 25 is up, each player can make as many moves in 30 seconds as they'd like, the 5 means that they can overstep that bound 5 times (by 30 second increments).
Compared to ~40 in a chess game would be 2 min per side / 20 moves = 10 seconds a move. (http://www.chessgames.com/chessstats.html)