In the following reaction product 'P' is : - $R-CO-Cl \xrightarrow[Pd-BaSO_4]{H_2} P$

Hydrogenation of an acid chloride over palladium on barium sulphate (poisoned with sulphur or quinoline) is called Rosenmund reduction.
$R-COCl + H_2 \xrightarrow{Pd-BaSO_4} R-CHO + HCl$
$BaSO_4$ poisons the catalyst so that the aldehyde formed is not reduced further to the alcohol.
So P is the aldehyde RCHO.