Astrologers divide 1 day in 24 parts and each part of roughly one hour is called 'Hora' muhurat. Seven planets from Sun to Saturn rule those parts of the day. Astrologically certain matters thrive in certain Hora of the day and fail in some other Hora of the day. Knowledge of Hora helps in ensuring that we do task in accordance with the nature of time and hence get successful results.
Here is Hora table which tells which planet rules particular period of a day. Table shows hour starting from Sunrise so you need to know sunrise. You can use AstroSage Sunrise calculator to know Sunrise at your city.
For example, suppose today on Monday, Sun is rising at 5:30 AM at your city. So starting from Sunrise time, first house will be governed by Moon, second hour by Saturn, third hour by Jupiter and so on.
You can click on the name of planet ruling Hora to know what is auspicious and what is inauspicious during that moment.