The reaction of a secondary alcohol with a hydrogen halide (like HBr) proceeds via an $S_N1$ mechanism involving a carbocation intermediate:

1. Protonation: The -OH group accepts a proton ($H^+$) to form water ($H_2O$), which is a good leaving group.
2. Carbocation Formation: Water leaves, generating a secondary ($2^{\circ}$) carbocation (e.g., from 3-methylbutan-2-ol, a $2^{\circ}$ carbocation is formed).
3. Rearrangement: A less stable carbocation rearranges to a more stable one if possible. Here, a 1,2-hydride shift occurs, converting the secondary carbocation into a more stable tertiary ($3^{\circ}$) carbocation.
4. Nucleophilic Attack: The bromide ion ($Br^-$) attacks the stable tertiary carbocation to form the major product, 2-Bromo-2-methylbutane (Tertiary Alkyl Halide).

Direct attack on the secondary carbocation yields the minor product.