Combat Round
Each combat round represents 6 seconds in the game world, and there are 10 rounds in 1 minute of combat. A round normally allows each character involved in a combat situation to act. Each time a character acts in a round’s normal order, it’s called her turn.
Each combat round’s activity begins with the character with the highest initiative count and then proceeds to the remaining characters in order of their initiative. When a character’s turn comes up in the initiative order, that character performs his entire round’s worth of actions. For some exceptions, see Other Actions on page 249; for example, delaying can change the order in which you take your turn. Regardless, in a normal combat round on her turn, a character can perform either a full action or a handful of shorter actions (see Actions in Combat on page 244 for more details about the actions characters can take).
When the rules refer to a “full round,” they usually mean a span of time from a particular initiative count in one round to the same initiative count in the next round. Effects that last a certain number of rounds end just before the same initiative count on which they began. Thus, if a spell with a duration of 1 round is cast on initiative count 14, it ends just before initiative count 14 on the following round.
Source
Core Rulebook pg. 239