A distribution from your retirement plan is simply defined as a payout of the amount of money that has accumulated in your retirement savings plan. This may include amounts you have contributed, the "vested" portion of any amounts your employer has contributed, plus any earnings on those contributions.
You will want to think carefully before making any decisions about the money in your retirement plan, as some choices may mean you have to pay more in income taxes on your distribution.
In general, you must begin taking distributions from your account by April 1 of the year following the year in which you turn 70½. Your distribution options may include keeping your money in your plan, enacting a direct rollover, or taking a cash distribution. Each option has different consequences.