Panchangam is a Sanskrit term, which mean five parts (Panch + Angam). It is a Indian Astrological almanac which folow 5 parts of Vedic calender as 1- Tithi (Date), Nakshatra (Moon's constellation or star), Yoga, Karan Yoga, Sun rise and set time. You can see here Panchang for each month.
A Nakshatra or Constallation is 1/27th part of the Zodiac, identified by the prominent star(s) in them. Moon completes one rotation in approximately 27 days. So Moon's average one day moment in the Zodiac (130 20') is span of one Nakshatra.
Zodiac is an imaginary belt stretching about 9degree North and 9degree South of the ecliptic within which the planets and the Moon remain in course of their movement. In case of the Moon, the deviation from the ecliptic is about +5o. The belt is divided into 12 equal zones each of 30o and each sector called a 'sign' or Rasi. According to the western system of reckoning (i.e. Sayana system) the first rasi i.e. Aries starts from the point of intersection of the ecliptic and the equator. there are 12 signs or rashi in both the systems, the first being Mesha according to Indian system.