Al-Walaa' الولاء means to be with the humble servants of Allah i.e. the Prophets and their divine successors and sincere followers. It is compulsory on every Muslim to be with the humble servants of Allah (SWT).
Al-Baraa' البراء or Al-Tabarri التبري من أعداء الله means to avoid, be away and never be with the enemies of Allah who are the enemies of the prophets and enemies of their divine successors and sincere followers.
These two concepts are part of obligatory duties on every Shia Muslim.
'Wassalam.