Surplus of capital account reveals sale of fixed assets and inflow of foreign currency. How does it implies net inflow of capital? Here capital refers to what?

Dear student, 
The  meaning of capital in terms of of capital account can be understood in terms of its components which are as follows:

• Foreign investment
• Loans
• Banking capital transactions
• Other capital 

There is said to be a net inflow of capital when there is a inflow of foreign currency.