What does the term al-Wala' (continuity) legally signify in performing Wudu?

Ablution (الوضوء): Sunnah Acts Part 2

• Facing the Qiblah during Wudu.
• Washing the next limb before the previously washed limb has dried.
• Repeating Wudu three times.
• Washing Wudu limbs while walking.