Q.A compound that undergoes bromination easily is :

The $-OH$ group in phenol is a powerful activating, ortho/para-directing group (it donates the oxygen lone pair into the ring by resonance), making phenol react with bromine far more readily than benzene, toluene, or benzoic acid.

Reactivity comparison for electrophilic bromination:

• Phenol: the $-OH$ group strongly activates the ring by resonance donation. Phenol reacts with bromine water at room temperature without any catalyst, instantly giving a white precipitate of 2,4,6-tribromophenol.
• Toluene: the $-CH_3$ group is only a weak activator (inductive/hyperconjugative effect), so toluene needs a Lewis-acid catalyst (e.g. $FeBr_3$) for bromination and is markedly less reactive than phenol. …