A point is a unit that measures how far the price of an instrument has moved. Its cash value depends on the market and the contract, but it always refers to a defined step in price.
On a stock, one point usually means USD 1 of price movement. On an index, a point is one whole number of index value, so an index rising from 5,000 to 5,025 has gained 25 points. On futures and other derivatives, the cash value of a point is set by the contract specification.
A point is not the same as a pip or a tick. A pip is the standard price unit in forex, normally the fourth decimal place; a tick is the smallest price move an instrument is allowed to make, set by the exchange. A point is the broader whole-number unit, used mainly for shares and indices.
A stock trades at USD 100 and later rises to USD 105.
It has moved 5 points:
USD 105 - USD 100 = 5 points
If you hold shares through that move, your profit or loss is the 5 points multiplied by the number of shares you hold.