In simple words
Mesha is the Vedic name for the sign Aries. It is ruled by Mars and is movable (a starter).
If your Moon was in Mesha, read "As your Moon sign". If Mesha was rising when you were born, read "As your lagna". Your chart page in Vedic mode shows both.
As your Moon sign
With the Moon in Mesha, your mind is quick, brave and eager for action. You recover fast from upsets, dislike waiting and feel best when you have a challenge to meet. Your emotional honesty is refreshing, though impatience can surface when life slows down.
As your lagna (rising sign)
With Mesha rising, you meet life head-on and are often seen as energetic and direct. Your body tends to be active and your approach pioneering. Learning to pace yourself keeps your vitality strong over the long run.
Growing with Mesha
Give each new venture one steady habit to support it. Courage lasts longest when it is paired with patience.
Vedic signs are measured from the stars (the sidereal zodiac), about 24° behind the Western ones. That is why many people's Vedic sign is one sign earlier than their Western sign.