Investment is using money to purchase assets in the hope that the asset will generate income over time or appreciate over time. Consumption, on the other hand, is when you purchase something with the immediate intent of personal use and with no expectation that it will generate money or increase in value.
Investment also helps grow the economy because it creates economic activity, such as the buying and selling of goods and services and employing people. Employed people get paid and either save, invest, or spend their money. If they spend their money, businesses make more profits. Businesses can then reinvest the profits in further business activities that expand the economy.
Of course, too much of a good thing can be bad. If everyone is investing, then no one is consuming. If no one is consuming, consumer-orientated businesses, such as restaurants and retail establishments, will suffer. This may lead to layoffs. The key is to find the proper balance between investment and consumption.