There are 2 option in margin grid, loan USDT or loan Token. Loan USDT means you borrow usdt and need to repaid the USDT again later. This means you need to make profit in USDT with the token, thus buying token with borrowed USDT and sell the token at profit price will give your more USDT. Loan Token means you borrow token and need to repaid the token later. This means you need to make profit in token number, so you short the token (sell the token now) , and buyback the token at lower price. Buying at lower price will give you more tokens amounts.