Sir i am a 12th bio student but i want to take btech cse so what are the basic knowledge that i should know before taking cse?

A friend of mine in his mid 80s, sold off his house and other investments in 2021 and has paid capital gains tax on the proceeds with proper filing of IT returns. The sum of Rs 4 crore he has parked in FDs and given his age moved to assisted living senior accommodation. His only son is overseas, an NRI for sevaral years and the son has no assets or interests/income in India. My friend wishes to transfer the proceeds of his house sale to his son and keep just sufficient funds for his limited expenses and sunset years. As per the Forex LRS, he can transfer 1.5 crores (up to 250K USD), but this will attract a TCS of 20% now. Is this a tax on foreign remittance? Or, can he file returns in June and claim the TCS back since the capital gains tax has already been paid on the sale of house two years back? It is not clear if the FM has introduced a new tax on Foreign Remittance or it is just a TCS that can be claimed as tax on income/capital gains was already paid to Govt. Please advise.