Baraa’ah is heartily dissociation from anyone whereas the manifestation of this dissociation is known as ‘Tabarra’.
[Qaamoos Alfaaz al-Quran, p. 45]
For instance, belief in Tauheed (Divine Monotheism) demands that we wholeheartedly dissociate from any other deity besides Allah. The statement ‘There is no god but Allah’ (Laa Ilaaha Illallah) is the manifestation of this belief.
Similarly, Baraa’ah is a part of our belief in Imamah which has two foundations –
1. Accepting the Mastership and Caliphate of the 12 successors of the Holy Prophet (peace be upon him and his holy family) after him
2. Dissociating from the opponents and enemies of these 12 Imams (peace be upon them) which is manifested by cursing them.
Like it has been mentioned in Aayat al-Kursi of the Holy Quran:
“Therefore the one who denies the Taaghoot (Satan) and believes in Allah has indeed held on to the strong rope.”
[Surah Baqarah (2): Verse 256]
Taaghoot (Satan) refers to those who usurped the rights of the progeny of Prophet Muhammad (peace be upon him and his holy family) and The Strong Rope is the Mastership of 12 Imams (peace be upon them).
[Tafseer al-Qummi, vol. 1, p. 84]