From the graph, as the term pV increases, the temperature increases; and when pV decreases the temperature decreases.

The term PV increases K$$\to$$L, so this involves heating and is an isobaric process.

It increases from N$$\to$$K, so this involves heating and is an isochoric process.

It decreases from M$$\to$$N, so this involves cooling and is an isobaric process.

It decreases from L$$\to$$M, so this involves cooling and is an isochoric process.