Why do total assets equal the sum of total liabilities and equity? Explain.

As we follow Double Entry System, where every debit has and equal and corresponsing credit. So, at the end of the day Assets will be equal to liabilities.

Assets means things/investments/ you have

Liabilities means which you have to pay

and any difference is owner's equity (In other terms = Net Profit + initial capital from owner)

Means anything under business property - anything business have to pay will be Owner's Equity

In double entry this relationship is well defined when we say Assets=Liabilities + Owner's Equity