What are the items shown on the credit side of the trial balance?and where do we enter the item office rent advance in trial balance?

Liabilities, Equity and Revnues are all credits. Assets and Expenses are the debits.

As for an advance on office rent, depends on whether the company paid it, or it got paid to the company. If the company paid it to someone else, that makes it a prepaid and an asset. If it got paid to the company as advanced revenue, then it's an unearned revenue and is a liability.

If a director takes a loan from the company(from the income and not from the paid up capital) suppose 50,000/-, where do we show this amount while preparing the financial account?