Profections are another time lord system based upon a simple progression in the order of the signs from a starting point. There are annual, monthly and daily profections for each planet or lot (arabic part as they are sometimes called). Each represents a subject (significator that gives signs for a subject matter), and the profection represents the unfolding of that subject through time.
Annual profections start on the first birth date and end on the following one. For instance, if you have the ascendant in Gemini, then the annual profection of the ascendant would be Cancer on your 2nd birthday, Leo on your 3rd, etc.
The monthly profections start wherever the annual profection starts and one month later go to the next sign, so if you were born on May 3rd, then on June 3rd it would be in the next sign, etc.
The daily profection has two types. Valens used a daily profection that goes from sign to sign for each day so that after 30 days the cycle of the zodiac has been completed 2 and 1/2 times. Then when the next monthly profection starts in a given place, the daily profection starts in the same place.
The other daily profection is more common in medieval literature where daily profections mimick the lunar motion, so that in 30 days the daily profection goes through 12 signs and ends up where it started, then skips to the next sign in the next monthly profection.
Profections represent the unfolding of a given subject matter through time. If you are interested in marriage, profect Venus, financial or health issues, profect the lot of fortune, or the ascendant. Valens said that whatever planet happens to be in that sign, (first consider natal planets, then transiting planets) shows the nature of the unfoldment of that issue (how it is progressing). For instance if profected lot of fortune comes to natal Mars, beware of health problems (cuts and bloodshed) and financial difficulties.
If no planet is found in the sign of the profection, then consider where it's lord is placed and planets transiting or witnessing that lord.