Socialism is when the means of production and distribution of goods or services are owned collectively or by a centralized government. I think either would be better than capitalism, but youre probably only thinking of the latter. Collective and government control can also take different forms.

Parks, libraries, public schools, fire departments, postal service, public infrastructure, public transportation, social security, etc are centralized government controlled socialist ideas "owned" by the people. Cooperatives are independent, stateless market socialism, owned by its members/workers and democratically controlled. I think its pretty easy to see how cooperatives are a direct alternative to capitalism and involve the economy and markets, but there's more a centralized government can do too. Namely nationalization of industries like oil/gas, railways, airlines, telecommunications, electric power, media, banks, housing etc. Which all also involve the economy and can be democratically controlled.

Capitalism is, succinctly, about how having capital allows an individual to increase their capital, and allows wealthy individuals to accumulate more and more wealth.