Rudra rule this day; fasting, devotional activities, and remembrance of the Supreme Lord are very favourable. This day has special religious significance in Hinduism and Jainism—usually observed by fasting.
Shukla Ekadashi is the name for the 11th Tithi (lunar day). It's the 11th Tithi of Shuklapaksha. It's nature is Anand Prada, which can be interpreted as "inculcates happiness", "leads to Ananda". It's good for following works: marriage; religious works, Alankar, Upanayana, Devotsava; Vrata, fasting, completion of fasts; jewellery; painting, learning of sculpturing, clothes designing, dress, dance; travel; enter, starting of house, manufacturing of drinks, trade. This day has special religious significance in Hindu tradition, usually it's observed by fasting and almost every Ekadashi has it's own meaning and purpose.
Lagna (ascendant or rising sign) during Shukla Ekadashi becomes Tithi Shoonya (Lagna which is ruined by Tithi) for times when it is Dhanu (Sagittarius) or Meena (Pisces). Rohini Nakshatra also becomes Tithi Shoonya if it falls on Shukla Ekadashi. It's considered that all auspicious works done during Tithi Shoonya periods will be destroyed.