A taxable account for buying and selling investments like stocks and funds.
A brokerage account lets you invest in stocks, bonds, ETFs, and mutual funds without the contribution limits or withdrawal rules of retirement accounts. Gains are taxable in the year you realize them, but there is no penalty for accessing the money. It is the standard place to invest beyond maxed-out tax-advantaged accounts, or for goals before retirement age.
After maxing a 401(k) and IRA, additional investing often goes into a taxable brokerage account.