Complex sentence: Hindu scriptures teach that it is especially important to avoid all beans and all grains on this day because on the day of Ekadashi these two foods are contaminated by sin, and thus be aware to eat only fruits and vegetables and milk products on this day.
Split into simpler sentences: Hindu scriptures teach that it is especially important to avoid all beans and all grains on this day because on the day of Ekadashi these two foods are contaminated by sin. To follow the tradition of Ekadashi means that one will avoid all beans and grains and eat only fruits and vegetables and milk products on this day.