Does an economics degree teach you stock marketing?Watch
An economics degree teaches you the theoretical concepts behind the management of scare resources in order to maximise a goal (usually profit). If you're asking whether an economics degree provide any insight on how to invest, trade, or work in finance, there's very little. The most relevant study that would be related is in your first year of macroeconomics. Other than that, you might want to look into finance specialist modules, which are very much standard finance modules.
If you're aiming to learn about investments, I would say a degree in economics and finance/accounting and finance/finance will put you in good stead, but you don't need it if you want to learn how to invest yourself. If you want professional qualifications related to the finance sector, it will depend on the qualification. The only qualification that I know of requiring a degree of any sort (not specific to economics) is the Chartered Financial Analyst qualification (but you can do the IMC instead if you don't have a degree). Most other professional qualifications I have seen require A Levels or less to study.
Should you wish to study material regarding stock markets, I would recommend you choose the following modules:
Financial accounting, with emphasis on ratio analysis
Statistics - be it econometrics or business statistics
I would further recommend you study something regarding the following, be it during your degree or after:
Taxation - usually specific to a country
Auditing - maybe
How businesses work
Management accounting - issues surrounding accounting, financial management, and performance measurement
If you want information on specific jobs (e.g. investment management, investment analysis, stockbrokering), you might want to look them up on National Careers Service. If you need pointers, let me know.