While naming the IUPAC nomenclature of hydrocarbon compounds, we usually start with the naming from the rare i.e the functional group from the right hand side.

Consider CH\(_3\)CH\(_2\)COOCH\(_2\)CH\(_3\), this is an ester obtained from two compounds propanoic acid and ethanol.

On splitting CH\(_3\)CH\(_2\)COOCH\(_2\)CH\(_3\), we have CH\(_3\)CH\(_2\)COO / CH\(_2\)CH\(_3\) dividing the compound into two; CH\(_3\)CH\(_2\)COO - Propanoate and CH\(_2\)CH\(_3\) - ethyl

So while naming as mentioned earlier on, we start the naming from the rare(RHS), and then the other(LHS). Thus, the name of the compound is; ethylpropanoate.