When planning your finances, it is important to distinguish between savings and investments. The most common way of saving is into a bank account (‘deposit’ account) where the money can be accessed in an emergency, and for every £,$,€1 you put in, you will get £;$,€1 back and possibly some interest. In other words, the original capital is guaranteed.
Investments are designed to be held longer, usually at least 5 years and above. You need to be comfortable tying up this money for some time and should not consider investments unless you have some savings.