How Shuddhadvaita Philosophy is pure non Dualism while admits reality of the world and reality of souls?
Vallabhacharya was a critique of Sankara's Advaita philosophy. In his opinion, Sankara's Advaita was not strictly non-dual because of the presence of both Brahman and Maya. Vallabhacharya's main criticism was regarding the existence of the Maya. If you accept Maya or Avidya, which is the root cause of the existence, then it is basically dualism. Maya is something equivalent to the Prakriti of Sankhya. Maya is something that cannot reside in Brahman.
According to Vallabhacharya Brahman alone exists. That's why it is known as Shuddhadvaita or pure non-dualism. Brahman has three properties: sat (existence), chit (consciousness) and ananda (bliss). This world is a real manifestation (Avirbhava) of Brahman. However, despite going through this manifestation, Brahman remains changeless. This is known as "Avikrita Parinamvada".
Manifestation happens through the process known as "Tirobhava", which means Brahman hides some of its properties while it manifests. It is a process of full or partial concealment. Brahman with sat, chit and ananda is the Purushottama. This is the highest Brahman. He is Krishna. From Purushottoma, Akshara Brahman manifests. Akshara Brahman has sat and chit properties. Bliss is missing. From Akshara, Jivas emerge as numerous sparks emerge from a fire. That's why Jivas are real (sat) and conscious (chit), but they lack bliss (ananda). Matters have only one property - sat. They do not have consciousness or bliss. But nonetheless, they exist.