The Profit and Loss Account forms part of a business' financial statements, along with a Balance Sheet and other information.
It is a summary of business income and business expenses within a certain time frame. Although the most common time frame is one year, it could also be for a period of one month, three months, six months, two years - whatever you like!
You may hear it being called a P&L, Income Statement, Statement of Income, or similar.
The major components of a profit and loss account are income and expenses. We explore these in more detail here.