Step 1: Draw out the structure.
The compound is $CH_3-CH(CH_3)-CH_2-CH(OH)-CH_3$. It has an $-OH$ group and a methyl branch.
Step 2: Pick the longest chain.
The longest chain that holds the $-OH$ carbon runs through five carbons. So the parent name is pentanol.
Step 3: Remember the numbering rule.
The $-OH$ group is the main group, so we number the chain to give it the smallest possible number.
Step 4: Number from the correct end.
Starting from the end nearer the $-OH$, the carbon bearing $-OH$ is number 2. The methyl branch then sits on carbon 4.
Step 5: Check the other end.
If we numbered from the far end, the $-OH$ would be on carbon 4, a larger number. So our first choice is correct because 2 is smaller than 4.
Step 6: Build the full name.
We have a methyl group at carbon 4 and the $-OH$ at carbon 2 of pentane, giving 4-methylpentan-2-ol.
Step 7: State the final answer.
The IUPAC name is:
\[ \boxed{\text{4-Methylpentan-2-ol}} \]