In the below reaction, write for each reactant that undergoes oxidation or reduction and identify the type of reaction.
$BaS{O_4} + 4C \to BaS + 4CO$

Hint:The reaction which shows the removal of electrons and where the oxidation state of the atom increases is termed as an oxidation reaction. The reaction which shows the gain of electrons and where the oxidation state of the atom decreases is termed as reduction reaction.

Complete step by step answer:
The redox reaction is defined as the reaction where the transfer of electrons between the two reactant species takes place.
When the oxidation reaction and reduction reaction takes place simultaneously the resulting reaction is known as a redox reaction.
The reaction is shown below.
$Ba{S^4}{O_4}(s) + 4{C^0}(s) \to Ba{S^{ - 2}}(s) + 4{C^2}O(g)$
On the left side of the reaction, the oxidation state of sulfur is 4 and the oxidation state of carbon is 0. After the completion of the reaction, the oxidation state of sulfur changes to -2, and carbon changes to 2.
The reduction reaction is shown below.
${S^4} + 8{e^ - } \to {S^{ - 2}}$
In this reaction, sulfur gains eight electrons and changes its oxidation state from 4 to -2. This reaction is known as a reduction reaction.
The oxidation reaction is shown below.
$4{C^0} - 8{e^ - } \to 4{C^2}$
In this reaction, carbon loses its eight electrons and changes its oxidation state from 0 to 2. This reaction is known as an oxidation reaction.
The resulting reaction is known as a redox reaction.

Note:
The oxidizing agents are the agents or compounds which oxidizes another compound. The reducing agents are the compound that gets oxidized during the reaction. In this reaction $BaS{O_4}$ is the oxidizing agent and carbon is the reducing agent.