As others say @Rainbowskytoday are you in school? If so, then teachers or a careers adviser should be able to help.
In general, the advice is to choose the A levels that will lead to the career you want. If no specific career is in your mind, choose the ones you enjoy and will do well at. Ideally there will be a correlation anyway – as in, the chosen career will fit with the subjects you enjoy.
For example – if you want to be a doctor or a vet, choose biology and chemistry and any other. If you want to be an engineer, choose physics and maths.
If you love Eng lit or French or history or DT, choose those. It's important to consider future plans when choosing A level subjects; but for many 15yos there is no clear career in mind, understandably enough.
You can also pick A levels you have not studied before, such as (in many schools) psychology, sociology, philosophy, gov/politics, economics. IMHO it’s a good idea to look at the spec and talk to teachers before starting a totally new subject to make sure it is one you will enjoy and do well at. A lot of YP have a different idea of psych, for example, from the reality.