Taqwa Means:
To cleanse or purify the heart and the soul.  The following verse of the Quran Illustrates this:
By the sun and its brightness, by the moon as it follows it, by the day as it shows its brightness, by the night as it conceals it, by the heaven and its wondrous make, by the earth and all its expanse, and by the soul and He Who perfected it in proportion, then He showed it what is wrong for it and what is right for it - indeed he succeeds who purifies it, and he fails who corrupts it."
 [Ash-Shams 91:1-10]