What is Hora or Horas means?  

If we divide the duration of day (sunrise to sunset) into twelve equal parts and similarly divide the duration of night (sunset to next sunrise) into twelve equal parts we get 24 sub divisions of a day called Horas. There are twelve Horas in the day and twelve in the night. The day lord next by 6th lord and so on rules first hora of the day. 

The following hora chart shows the day and the planet ruling the hora at any given time of the day.