Talking is engaging in dialogue with characters. In some games the dialogue is selectable, so the player can guide himself through the conversation and learn more or less as he wishes. In others it is hard-wired. In theory this provides narrative to the player.
In practise, it is actually more like flipping switches in a large room to find out which one activates the overhead light. Talking tends to be a permutation exercise in which the content matters a lot less than getting to the right on/off combination which lets the player proceed. The player is simply asked to choose X or Y repeatedly and with the sensation that the game will steer toward Y anyway.
Talking is therefore usually busywork.
